Front End Interview Flashcards

1
Q

What did you learn yesterday/this week?

A

Open Ended, Practice Answering

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2
Q

What excites or interests you about coding?

A

What really excites me about coding is the inherent puzzle-solving nature of it. It’s like tackling a complex puzzle where anything feels possible if you can figure it out. The thrill of finally uncovering the cause of a slippery bug is immensely satisfying. Moreover, I enjoy the creative aspect of coding, particularly in creating tactile and beautiful interfaces and animations. It’s this combination of logical problem-solving and the opportunity to express creativity that keeps me engaged and passionate about coding.

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3
Q

When building a new web site or maintaining one, can you explain some techniques you have used to increase performance?

A

Lazy Loading: For resources that are not immediately needed, I make use of lazy loading. This includes images, scripts, or components, which are loaded only when they are about to be displayed.

Optimizing Images: I ensure that images are compressed and optimized for the web. This involves choosing the right file format, using responsive images, and employing tools like ImageMagick or services like TinyPNG to reduce file sizes.

Content Delivery Network (CDN): Utilizing a CDN helps in distributing static assets across multiple servers geographically. This minimizes latency and accelerates content delivery to users.

Performance Monitoring: Regularly monitoring the application’s performance using tools like Google Lighthouse, WebPageTest, or browser developer tools helps identify areas that need improvement.

Responsive Design: Ensuring that the web application is responsive and adapts well to various screen sizes not only improves user experience but can also positively impact performance. Responsive design often involves using a single set of HTML and CSS for all devices, rather than creating separate versions for desktop and mobile. This can result in fewer HTTP requests because there’s less need to download different sets of assets for different devices.

Caching Strategies: Implementing caching mechanisms, both on the client side (browser caching) and server side (HTTP caching), is crucial. This reduces redundant requests and speeds up subsequent page loads.

Browser Rendering Optimization: I pay attention to the critical rendering path, optimizing the order in which assets are loaded to ensure that the most important content is displayed as quickly as possible.

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4
Q

What is a recent technical challenge you experienced and how did you solve it?

A

Open Ended, Practice Answering

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5
Q

What is the critical rendering path?

A

The critical rendering path is the sequence of steps browsers take to convert HTML, CSS, and JavaScript into rendered pixels on the screen. Optimizing the critical rendering path is crucial for improving page load times and providing a faster, more responsive user experience. Here are the key stages in the critical rendering path:

  1. HTML Parsing and DOM Construction:

The browser parses the HTML document to create the Document Object Model (DOM), a tree-like structure representing the structure of the webpage. This process is called HTML parsing. The DOM is crucial for rendering and manipulating the content on the page.

  1. CSS Parsing and Style Computation:

As the browser encounters CSS stylesheets, it parses and constructs the CSS Object Model (CSSOM). The CSSOM contains information about the styles applied to elements on the page. The browser then combines the DOM and CSSOM to create the Render Tree, a tree structure that represents the visual hierarchy of the page.

  1. Layout (Reflow):

The browser calculates the layout of elements on the page, determining their position and size. This process is often referred to as reflow. Changes to the layout trigger recalculations, making it a computationally expensive operation.

  1. Paint:

The browser paints the pixels on the screen based on the information from the Render Tree and layout calculations. This process is known as paint. The painted pixels make up the visual representation of the webpage.

  1. Composite:

Finally, the browser combines the painted layers to create the final rendered image on the screen. This process is called composite.

Optimizing the critical rendering path involves minimizing the time spent in each of these stages. Here are some strategies to achieve this:

  1. Reduce the Number of Requests: Minimize the number of HTTP requests by combining and minimizing CSS and JavaScript files. This reduces the time spent in downloading resources.
  2. Prioritize Critical Resources: Load critical resources, such as stylesheets and scripts needed for above-the-fold content, as early as possible to speed up rendering of the initial view.
  3. Async and Defer Loading: Use the async and defer attributes for script tags to control when JavaScript is executed. This helps avoid blocking the HTML parsing and rendering process.
  4. Optimize CSS and JavaScript: Minify and compress CSS and JavaScript files to reduce their size. This speeds up the download and parsing process.
  5. Avoid Render-Blocking Resources: Identify and optimize resources that block rendering, such as large images or synchronous JavaScript that delays the rendering process.
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6
Q

Explain what the DOM is

A

The DOM, or Document Object Model, is a programming interface for web documents. It represents the structure of a document as a tree of objects. Each object corresponds to a part of the document, like elements, attributes, and text content. It allows us to interact with and manipulate the content, structure, and style of a web page using JavaScript.

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7
Q

Can you share some recent SEO techniques you’ve used?

A

Sure thing! Lately, I’ve been big on semantic HTML, making sure our content structure is clear for search engines. Also, optimized metadata is key – crafting catchy titles and descriptions with our target keywords.

Responsive design is a must for mobile-friendly vibes, and optimizing images, not just for looks but also for search engines. Oh, and speeding things up with page load tricks – code splitting, CSS and JS minification, you know the drill.

Adding structured data markup for that extra search engine love and keeping our URLs clean and keyword-friendly. Internal linking helps guide search engines through our content, and regular updates keep things fresh. And, of course, solid keyword research to know what users are looking for.

It’s all about keeping things user-friendly while speaking the language search engines love!

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8
Q

What actions have you personally taken on recent projects to increase maintainability of your code?

A

One big move in our Vue lobby redesign was breaking down complex components into smaller, reusable ones. This modular approach makes it easier to understand, update, and troubleshoot.

I’ve also been keen on keeping a consistent coding style across the project, using Vue’s style guide. It might seem minor, but it makes collaboration smoother and the codebase more cohesive.

Documentation is another hero in my toolkit. I make sure to document not just the how, but also the why behind certain design decisions. It’s a lifesaver for future developers – or future me!

Implementing Vuex for state management has been a game-changer. It centralizes the state logic, making it easier to track and manage, especially as the casino lobby gets more complex.

All these efforts might add a bit to the initial development time, but they pay off big time in the long run by making the codebase more robust and maintainable.

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9
Q

Talk about your preferred development environment.

A

I’m a big fan of Visual Studio Code. The extensions and ecosystem it offers are a game-changer for Vue development. The Vetur extension, in particular, makes Vue.js development a breeze with features like syntax highlighting, IntelliSense, and template validation.

For version control, I rely on Git, and platforms like Bitbucket for collaborative projects.

As for terminals, I often use the integrated terminal in VS Code. It’s convenient, and I can run commands without switching between windows.

For versioning and dependency management, npm does the job well, especially when working with Vue CLI for project scaffolding.

Overall, a lightweight and efficient setup with VS Code at the center has been my go-to for a while now. It strikes the right balance between functionality, ease of use, and community support.

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10
Q

Which version control systems are you familiar with?

A

I’m well-versed in Git, which we use for day-to-day version control tasks like committing, pushing, and pulling changes. I’m comfortable navigating Git repositories, managing branches, and resolving merge conflicts.

In our collaborative workflow, I’m familiar with using Bitbucket for pull requests and code reviews. Bitbucket complements it by providing a user-friendly interface for collaboration and code management.

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11
Q

Can you describe your workflow when you create a web page?

A

Absolutely. Here’s a simplified overview of my workflow:

I start by setting up the project using Vue CLI or a similar tool. This involves creating the project structure, configuring dependencies, and establishing a version control repository.

Planning and Wireframing:

Before diving into code, I often sketch out a rough wireframe of the page layout and structure. It helps me visualize the components and overall design.

Vue Component Creation:

I break down the page into Vue components. Each component is responsible for a specific part of the UI, promoting reusability and maintainability.

Styling with CSS and Vuetify:

I use CSS and possibly a component library like Vuetify to style the components. Vuetify’s pre-built components and responsive design elements save time and ensure consistency.

Adding Interactivity with Vue.js:

I leverage Vue.js for dynamic and interactive elements. Directives, event handling, and data binding allow me to create a responsive and engaging user experience.

API Integration:

If the page requires data from an API, I set up API calls using tools like Axios. Vue’s lifecycle hooks, such as mounted, are handy for fetching data when the component is ready.

Optimizing for Performance:

I optimize the page for performance by considering aspects like lazy loading, code splitting, and image optimization. This ensures a smooth user experience, especially on slower connections.

Version Control with Git and Bitbucket:

Throughout the process, I commit changes regularly using Git. For collaborative projects, I create branches for features or bug fixes and use Bitbucket for pull requests and code reviews.

Documentation:

I document the code, especially complex logic or decisions, to make it easier for other developers (or future me) to understand the implementation.

Review and Deployment:

Before deployment, I conduct a thorough review, checking for code quality, responsiveness, and cross-browser compatibility. Continuous integration tools can automate this process.

Deployment:

Finally, I deploy the web page to the production environment, ensuring that it aligns with our deployment strategies and doesn’t disrupt the live application.
This workflow allows for a systematic and collaborative approach to web development, combining planning, coding, testing, and deployment in a structured manner.

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12
Q

If you have 5 different stylesheets, how would you best integrate them into the site?

A

Great question. Here’s how I would approach integrating five different stylesheets into a site:

Bundle and Minify:

I’d first concatenate and minify the individual stylesheets into a single, optimized file. This reduces the number of HTTP requests, improving page load times.

Organize Styles:

Before bundling, I’d organize the stylesheets based on their purpose. For example, separate global styles, component-specific styles, and third-party library styles. This maintains a clear and modular structure.

Load Asynchronously or Defer:

To avoid render-blocking, I’d load non-critical stylesheets asynchronously or defer their loading until after the initial page render. This can be achieved using techniques like the async attribute for <link></link> tags or JavaScript to dynamically load styles.

Conditional Loading:

Depending on the use case, I might conditionally load certain stylesheets only for specific pages or components. This can be achieved through dynamic imports or server-side logic.

Maintainability:

Lastly, I’d document the purpose of each stylesheet and any conventions used for styling. This documentation aids in future development and makes it easier for other team members to understand and contribute to the codebase.

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13
Q

Can you describe the difference between progressive enhancement and graceful degradation?

A

Certainly. Both progressive enhancement and graceful degradation are strategies in web development to ensure a good user experience across different devices and browsers, but they approach it in different ways:

Progressive Enhancement:

Definition: Progressive enhancement starts with a basic, universally accessible version of a web page and then progressively adds more advanced features or enhancements based on the capabilities of the user’s device and browser.
Approach: The core functionality and content are delivered to all users, regardless of their device or browser capabilities. Then, additional enhancements, such as advanced styling, interactivity, or features, are layered on top for users with more capable devices and browsers.
Key Idea: It focuses on building a solid foundation that works everywhere and then enhances the experience for users with modern browsers or devices.

Graceful Degradation:

Definition: Graceful degradation, on the other hand, starts with a fully-featured and visually rich version of a web page designed for the latest browsers and devices. It then ensures that the page still functions reasonably well, albeit with fewer features or a simpler design, on older browsers or less capable devices.
Approach: The primary design and functionality are created for the latest technologies. If a user’s device or browser doesn’t support certain features, the experience gracefully degrades to a simpler but still functional version.
Key Idea: It focuses on delivering the best experience possible for users with modern technologies and gracefully handling the limitations of older technologies.

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14
Q

How would you optimize a website’s assets/resources?

A

Optimizing a website’s assets is crucial for improving performance and user experience. Here’s how I would approach it:

Image Optimization:

Compress and resize images without compromising quality. Use modern image formats (WebP) where supported. Lazy loading images is also effective in reducing initial page load times.
Minification and Compression:

Minify CSS, JavaScript, and HTML files to remove unnecessary characters like whitespace and comments. Additionally, enable server-side compression (gzip or Brotli) to reduce file sizes during transmission.
Browser Caching:

Leverage browser caching to store static assets locally on the user’s device. This reduces the need to download the same resources on subsequent visits, improving load times.
Code Splitting:

Implement code splitting to break down large JavaScript bundles into smaller, more manageable chunks. Load only the code required for the current page, enhancing performance.
Async and Defer Loading:

Use the async and defer attributes for script tags to control when JavaScript is executed. This prevents scripts from blocking the rendering of the page, especially for non-critical functionality.
Content Delivery Network (CDN):

Utilize a CDN to distribute assets across multiple servers globally. This reduces latency and ensures faster delivery of content to users, especially those geographically distant from the server.
Critical CSS and Fonts:

Inline critical CSS to ensure faster rendering of above-the-fold content. Asynchronous loading or utilizing the font-display property for web fonts can prevent them from blocking page rendering.
Reduce HTTP Requests:

Minimize the number of HTTP requests by combining and optimizing assets. Use CSS sprites for multiple small images and consider using icon fonts or SVGs instead of individual image files.
Prefetching:

Implement resource prefetching for critical assets that will be needed on subsequent pages. This reduces the perceived load time when users navigate to other parts of the site.
Responsive Design:

Design with a mobile-first approach to ensure that assets are appropriately sized for different devices. Use media queries and responsive images to adapt to various screen sizes.
Monitor and Analyze:

Regularly monitor website performance using tools like Google PageSpeed Insights, Lighthouse, or WebPageTest. Analyze the results and make adjustments based on performance bottlenecks.

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15
Q

How many resources will a browser download from a given domain at a time?
What are the exceptions?

A

Browsers usually follow a limit of six concurrent connections per domain to manage resource downloads efficiently. This means that, by default, the browser will fetch up to six resources simultaneously from the same domain. However, there are some exceptions and considerations:

Subdomains: Browsers often treat subdomains as separate entities, allowing an additional set of six concurrent connections. For instance, if you have a main domain like example.com and serve images from img.example.com, it may open six connections for each.

HTTP/2: With the adoption of HTTP/2, browsers can multiplex multiple streams over a single connection, reducing the impact of the six-connection limit. This is especially beneficial for modern websites that utilize HTTP/2.

Domain Sharding (deprecated): In the past, developers used domain sharding to overcome connection limits by spreading resources across multiple domains. However, this practice is now considered outdated, and newer technologies like HTTP/2 have made it less necessary.

Connection Pooling: Browsers may use connection pooling to reuse existing connections for subsequent requests, optimizing resource retrieval by efficiently managing multiple connections.

These considerations are essential when optimizing website performance, ensuring that the browser can fetch resources in a way that aligns with network and server constraints.`

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16
Q

Name 3 ways to decrease page load (perceived or actual load time).

A

Optimize Images:

Compress and resize images to reduce their file sizes. Use modern image formats like WebP when possible. Implement lazy loading to defer the loading of images until they are about to be viewed, which significantly improves initial page load times.
Minify and Bundle Code:

Minify CSS, JavaScript, and HTML files to remove unnecessary characters, reducing file sizes. Additionally, bundle and concatenate files to reduce the number of HTTP requests. This not only speeds up the initial load but also benefits subsequent page views due to cached resources.
Prioritize Critical Rendering Path:

Streamline the critical rendering path by prioritizing the loading of essential resources for above-the-fold content. This includes inlining critical CSS to ensure that the initial view is styled quickly. Consider asynchronous loading of non-essential scripts or deferring their execution until after the initial rendering.
Implementing these strategies helps in optimizing both perceived and actual page load times, contributing to a faster and more responsive user experience.

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17
Q

If you jumped on a project and they used tabs and you used spaces, what would you do?

A

In such a scenario, I would prioritize consistency to maintain a clean and cohesive codebase. Here’s how I would approach it:

Follow Existing Convention:

I would adhere to the existing code convention, which in this case is using tabs. Consistency within the codebase is crucial for readability and collaboration.
Configure Editor Settings:

I would configure my code editor to use tabs instead of spaces for this particular project. Most modern code editors allow users to customize indentation settings on a per-project basis.
Respect Team Norms:

I would discuss the indentation style with the team and understand the reasons behind their choice. If there’s a strong preference for tabs, I would respect that and adapt to the team’s norms.
Automated Formatting:

To avoid manual formatting conflicts, I might suggest incorporating a code formatter, such as Prettier or ESLint, into the project. This ensures consistent formatting automatically and helps prevent style-related issues during code reviews.

In essence, the key is to prioritize consistency and effective collaboration within the existing project norms. It’s crucial to communicate with the team, understand their preferences, and find a solution that maintains a unified and readable codebase.

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18
Q

Describe how you would create a simple slideshow page.

A

Certainly! Let’s break it down:

HTML Structure:

I’d start with the basic HTML structure, setting up a container for the slideshow and including image elements for each slide. Each slide is wrapped in a div with a common class, and I’ve added navigation arrows for the user to manually navigate through the slides.
CSS Styles:

In the CSS, I’ve styled the slideshow container to be centered on the page and defined the basic styles for the slides. I’ve added styles for the navigation arrows to make them visible and positioned them on the sides of the slideshow.
JavaScript Logic:

For the JavaScript part, I’ve set up a simple logic to handle the slideshow. The showSlides function hides all slides and displays the current one based on the slide index. The changeSlide function is called when the user clicks on the navigation arrows, updating the index accordingly.
Automatic Slideshow:

I’ve included a setInterval function that automatically changes the slide every 3 seconds, creating a basic automatic slideshow effect.
Initial Display:

Finally, I make sure to call showSlides initially to display the first slide when the page loads.
This is a straightforward setup that can be expanded upon based on specific requirements. For instance, you could add captions, customize transitions, or fetch slides dynamically from a server. The code provides a foundation that can be built upon to create a more feature-rich slideshow experience.

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19
Q

If you could master one technology this year, what would it be?

A

I would choose to master data visualization, particularly diving into libraries and frameworks like D3.js or Chart.js. The reason behind this choice is my genuine interest in exploring the power of visual representation in conveying complex data insights.

Data visualization plays a crucial role in making information more accessible and understandable. It’s not just about presenting numbers; it’s about telling a compelling story through visuals. Whether it’s interactive charts, graphs, or dynamic dashboards, the ability to translate data into meaningful visuals is a skill that I believe can bring immense value to any project.

I haven’t delved deeply into data visualization yet, but the potential to unlock new insights and improve decision-making processes excites me. With the increasing emphasis on data-driven approaches in various industries, mastering data visualization would not only align with current trends but also open up exciting possibilities for creating impactful and user-friendly applications.

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20
Q

Explain the importance of standards and standards bodies.

A

Standards and standards bodies play a pivotal role in the world of software development and technology for several reasons:

Interoperability:

Standards provide a common set of rules and specifications that ensure interoperability between different systems, software, and devices. This is crucial for creating a cohesive and interconnected digital ecosystem.
Compatibility:

Standards enable compatibility between various technologies and platforms. Developers can rely on standardized protocols and formats, reducing the likelihood of conflicts and ensuring that software and hardware components work seamlessly together.
Innovation and Collaboration:

Standards encourage innovation by providing a foundation upon which developers can build. When everyone follows the same standards, it fosters collaboration and the exchange of ideas, leading to the creation of more robust and versatile technologies.
Market Growth:

Standardization accelerates market growth by creating a level playing field. When products adhere to common standards, it becomes easier for consumers to adopt new technologies, fostering competition and driving advancements in the market.
Security and Reliability:

Standards often include best practices for security and reliability. Adhering to established standards helps developers implement robust security measures and build reliable systems, reducing vulnerabilities and enhancing overall system integrity.
Regulatory Compliance:

Standards bodies often work closely with regulatory authorities to establish guidelines and regulations. Adhering to these standards ensures that software developers comply with legal requirements and industry regulations, mitigating risks and ensuring ethical practices.
Long-Term Maintenance:

Standards contribute to the long-term maintainability of software and systems. When technologies follow established standards, it becomes easier to update, upgrade, or replace components without disrupting the entire ecosystem.
Global Collaboration:

Standards bodies facilitate global collaboration by bringing together experts from around the world to define and refine standards. This international collaboration ensures that standards are comprehensive, unbiased, and applicable across diverse environments.
In essence, standards and standards bodies provide a foundation for a reliable, interoperable, and innovative technological landscape. They are a cornerstone of the software development process, promoting consistency, compatibility, and the overall advancement of the industry.

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21
Q

What is Flash of Unstyled Content? How do you avoid FOUC?

A

A Flash of Unstyled Content (FOUC) occurs when a web page briefly renders with unstyled or default styles before applying the intended styling. This phenomenon is often noticeable during the initial loading of a web page and can lead to a less-than-optimal user experience.

To avoid FOUC, here are some strategies:

Properly Organized Stylesheets:

Ensure that your stylesheets are organized and loaded in a logical order. Critical styles, especially those for above-the-fold content, should be loaded first to style the essential parts of the page before less critical styles.
Inline Critical CSS:

Inline critical CSS directly within the HTML for above-the-fold content. This way, the essential styling is applied immediately, mitigating the impact of FOUC during the initial page load. Tools like Critical CSS or critical path CSS generators can assist in this process.
Preloading Stylesheets:

Use the preload attribute to hint to the browser that certain stylesheets are crucial for rendering the page. This allows the browser to fetch and prioritize these stylesheets, reducing the likelihood of FOUC.
Optimize Loading Order:

Optimize the loading order of scripts and stylesheets. Scripts that manipulate the DOM or apply styles should be deferred or loaded asynchronously to prevent them from blocking the rendering of the page.
Responsive Design:

Implement a responsive design approach, ensuring that your styles adapt well to various screen sizes. This helps prevent layout shifts that might occur if the styles are applied after the initial rendering.
Media Queries:

Use media queries to apply styles based on the user’s device characteristics. This allows you to tailor the styling for different screen sizes and resolutions, avoiding unnecessary layout adjustments.
Browser Caching:

Leverage browser caching for your stylesheets. Once a user visits your site, the stylesheets can be cached locally, reducing the need to download them again on subsequent visits and decreasing the chances of FOUC.
By employing these strategies, you can minimize the occurrence of FOUC and ensure a smoother and more visually consistent user experience during the loading of your web pages.

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22
Q

Emily, could you explain what ARIA is and how it helps make websites accessible? Also, what about screen readers?

A

ARIA stands for Accessible Rich Internet Applications. It’s like this extra layer of information we add to our HTML to help out folks using assistive tech, especially screen readers. ARIA makes sure dynamic stuff on our site, like interactive buttons or single-page app elements, gets properly interpreted and described by those assistive tools.

And speaking of screen readers, they’re these awesome tools that turn digital text into spoken words or Braille. They’re a game-changer for users with visual impairments, helping them navigate and understand what’s on a webpage.

I’d make sure I’m using semantic HTML, you know, giving elements like buttons or navigation a proper meaning. Then, I’d sprinkle in some ARIA roles and attributes for that extra context.

Focus styles are crucial too. When you’re tabbing through a site, it’s essential to know where you are. So, I’d make sure all interactive stuff has a clear focus style.

And let’s not forget descriptive text for things like images. Gotta use the alt attribute to give a brief, meaningful description. Oh, and keyboard navigation—everything on the site should be reachable and usable just with a keyboard.

Finally, regular testing, especially with real users who rely on assistive tech, keeps things in check. It’s like making sure your site is a welcoming place for everyone who visits.

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23
Q

Explain some of the pros and cons for CSS animations versus JavaScript animations.

A

CSS Animations:

Pros:

Ease of Use: CSS animations are super straightforward. You can define them in your stylesheets using keyframes, and they’re easy to understand and implement.

Performance: Generally, CSS animations tend to be more performant, especially for simpler animations. Browsers can optimize them well, and you don’t need to worry about scripting overhead.

Hardware Acceleration: CSS animations often leverage hardware acceleration, making them smoother and more efficient, especially for transitions like opacity or transforms.

Cons:

Limited Control: While CSS animations are great for simple transitions, they might feel limiting if you need more complex, interactive animations. Controlling them dynamically based on user interactions can be a bit challenging.

Browser Compatibility: Some older browsers may not support the latest CSS animation features, so you might need fallbacks or consider alternative approaches for broader compatibility.

JavaScript Animations:

Pros:

Full Control: With JavaScript, you have complete control over animations. You can create intricate, dynamic animations based on user interactions or specific events, offering a lot of flexibility.

Interactivity: JavaScript animations shine when it comes to interactive animations. You can respond to user input, create complex sequences, and tie animations directly to your application logic.

Cross-browser Compatibility: JavaScript animations are more likely to work consistently across different browsers, making them a safer bet for intricate animations in complex projects.

Cons:

Performance Overheads: While modern browsers have become more efficient, complex JavaScript animations can still introduce performance overhead, especially on less powerful devices.

Learning Curve: Working with JavaScript animations might have a steeper learning curve, especially for beginners. It involves understanding the DOM, managing states, and handling various events.

Code Maintainability: Complex JavaScript animations can sometimes lead to more code, potentially making it harder to maintain and debug compared to a concise CSS animation.

So, it really depends on the context. For simple, performant transitions, CSS animations are fantastic. But when you need dynamic, interactive animations, JavaScript gives you the power and control you might be looking for.

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24
Q

What does CORS stand for and what issue does it address?

A

CORS stands for Cross-Origin Resource Sharing. It’s a security feature implemented by web browsers that helps control how web pages in one domain can request and interact with resources on another domain.

The issue CORS addresses is related to security and preventing malicious activities that could occur if web pages were allowed to make unrestricted requests to different domains. Without CORS, a script on one domain might be able to make requests to another domain on behalf of a user, potentially leading to security vulnerabilities and unauthorized access to sensitive data. CORS sets up a set of rules and headers that both the client and server must follow, allowing secure communication between different origins while protecting user data and privacy.

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25
Q

How did you handle a disagreement with your boss or your collaborator?

A

a designer has proposed a visually appealing design that you believe might have performance or mobile-friendliness challenges.

In this scenario, I would:

Understand the Design Choices:

First, I’d seek to understand the rationale behind the design choices. It’s important to acknowledge the designer’s expertise and the creative aspects they bring to the project.
Raise Concerns Tactfully:

Instead of outright disagreeing, I would tactfully express my concerns about the potential performance or mobile usability issues. I might frame it as a discussion, emphasizing our shared goal of delivering a high-quality, user-friendly product.
Provide Data and Examples:

To support my concerns, I’d provide data or examples that illustrate the potential challenges. For instance, I might showcase performance metrics or demonstrate how the design might behave on different devices.
Propose Alternatives:

Rather than just pointing out issues, I’d offer alternative solutions or adjustments that align with the design’s aesthetic while addressing the performance or mobile concerns. This could be a collaborative process where we find a balance between design and functionality.
Encourage Collaboration:

Emphasizing collaboration is crucial. I would invite the designer to work together to find a solution that meets both the design vision and the technical requirements. This collaborative approach fosters a positive working relationship.
Involve Others if Needed:

If the disagreement persists, involving other team members, such as a project manager or a front-end developer, could provide additional perspectives and insights.
Test and Iterate:

Once a decision is made, I’d be open to testing and iterating on the design. This allows us to validate our choices and make adjustments based on real-world performance and user experience.
Remember, in a collaborative environment, everyone’s input is valuable. By approaching disagreements with respect, data-driven insights, and a collaborative mindset, we can find solutions that balance both design creativity and technical considerations.

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26
Q

What resources do you use to learn about the latest in front end development and design?

A

Social Media and Dev Accounts:

I follow key developers and industry accounts on platforms like Twitter. It’s a great way to catch wind of new technologies, best practices, and discussions within the community.
Email Subscriptions:

Subscribing to newsletters and email lists keeps my inbox filled with curated content. I get updates on articles, tutorials, and even event announcements. It’s like a personalized drip feed of knowledge.
Frontend Masters:

I’m a big fan of Frontend Masters. Their platform is a treasure trove of in-depth courses on various front-end technologies. It’s my go-to for deepening my skills and keeping up with emerging technologies.

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27
Q

What skills are needed to be a good front-end developer?

A

Being a front-end developer is quite a ride, and it requires a mix of technical and soft skills. Here’s what I’d consider essential:

HTML, CSS, and JavaScript:

These are the building blocks. Solid proficiency in HTML for structure, CSS for styling, and JavaScript for interactivity is the foundation of front-end development.
Responsive Design:

Knowing how to create websites that work seamlessly across different devices and screen sizes is crucial. Media queries and flexible layouts are your friends.
CSS Preprocessing:

Familiarity with CSS preprocessors like Sass or Less can enhance your styling workflow. It helps manage styles more efficiently and adds some handy features.
Version Control/Git:

Understanding version control systems, especially Git, is a must. It helps manage code changes, collaborate with others, and roll back if needed.
Web Performance:

Awareness of web performance optimization techniques ensures your websites are not just functional but also fast and efficient. This includes minimizing requests, optimizing images, and more.
Front-end Frameworks:

Experience with front-end frameworks like React, Vue, or Angular is increasingly valuable. They simplify the development process and are widely used in industry projects.
Browser Developer Tools:

Knowing how to leverage browser developer tools for debugging and profiling is essential. It’s like having a superpower for fixing issues and optimizing performance.
Command Line/CLI:

Being comfortable with the command line or CLI is handy. It streamlines tasks like package management, running scripts, and interacting with version control.
Build Tools and Module Bundlers:

Familiarity with build tools like Webpack and module bundlers like Parcel is important. They help automate tasks, bundle dependencies, and optimize code for production.
Testing/Debugging:

Knowing how to write and run tests ensures the reliability of your code. Debugging skills are equally crucial for finding and fixing issues efficiently.
Soft Skills:

Communication and collaboration are key. As a front-end developer, you’ll often work closely with designers, back-end developers, and other team members. Being able to articulate your ideas and understand others is crucial.
Continuous Learning:

The tech landscape evolves rapidly. A willingness to learn and adapt is perhaps the most critical skill. Whether it’s a new framework, tool, or best practice, staying curious keeps you at the top of your game.
Balancing these technical and soft skills is what makes a front-end developer not just good but great. It’s an exciting and dynamic field, and being well-rounded opens up endless possibilities for creativity and innovation.

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28
Q

What role do you see yourself in?

A

I envision myself as a Senior Front-End Developer, acting as a bridge between designers and developers. In this role, my goal would be to facilitate seamless collaboration, ensuring that design visions are translated into functional and efficient code. I’d love to mentor junior developers, sharing my knowledge and helping them navigate the intricacies of front-end development.

Additionally, I’m eager to explore more of the backend world. While my expertise lies in front-end technologies, having a deeper understanding of the backend would make me a more well-rounded developer. It would enhance my ability to contribute to full-stack projects, understanding the end-to-end development process.

Being in a leadership position where I can guide and inspire others while continuously learning and expanding my skill set is the trajectory I see for myself. It’s about striking that balance between technical expertise, mentorship, and a perpetual thirst for knowledge in this ever-evolving field.

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29
Q

Explain the difference between cookies, session storage, and local storage?

A

Cookies:

Purpose: Cookies are small pieces of data stored in a user’s browser. They’re commonly used for tracking user authentication, session management, and storing user preferences.
Lifetime: Cookies have an expiration date and can persist across multiple sessions. You can set their expiration when creating them, and they will be sent with every subsequent request to the same domain.
Size Limit: Limited to around 4KB of data.
Session Storage:

Purpose: Session Storage is designed for the duration of a page session. It’s a separate storage area for each tab or window, and the data is cleared when the session ends.
Lifetime: Persists only for the duration of the page session. Closing the tab or window typically clears the data.
Size Limit: Usually larger than cookies but still limited compared to Local Storage.
Local Storage:

Purpose: Local Storage provides a way to store key-value pairs in a web browser with no expiration time. It’s commonly used for persisting user preferences or caching.
Lifetime: Persists even when the browser is closed and reopened. It remains until explicitly cleared by the user or the application.
Size Limit: Larger storage capacity compared to cookies and session storage, typically around 5-10MB.
Comparison:

Scope:

Cookies are sent with every HTTP request, including image requests, which can affect performance.
Session Storage is limited to a particular tab or window.
Local Storage is domain-wide and persists across tabs and windows.
Lifetime:

Cookies and Local Storage persist beyond the current session.
Session Storage is short-lived and tied to the duration of a page session.
Storage Size:

Cookies have a size limit of around 4KB.
Session Storage is usually larger than cookies but still limited.
Local Storage offers a larger capacity, typically around 5-10MB.
Use Cases:

Cookies are often used for authentication, tracking, and storing small pieces of data.
Session Storage is suitable for data that needs to be available for a shorter duration.
Local Storage is great for persisting user preferences and caching larger amounts of data.
Understanding these storage options allows developers to choose the most suitable one based on the requirements of their application.

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30
Q

Can you explain what happens when you enter a URL into the browser?

A

URL Parsing:

When you enter a URL (Uniform Resource Locator) into the browser’s address bar, the browser first parses the URL to understand its components. This includes the protocol (HTTP or HTTPS), domain (e.g., www.example.com), path, and any query parameters.
DNS Resolution:

The browser checks its local cache to see if it already has the IP address associated with the domain. If not, it initiates a DNS (Domain Name System) resolution. DNS translates the human-readable domain (e.g., www.example.com) into an IP address that computers understand.
HTTP/HTTPS Handshake:

If the URL begins with “http://” or “https://”, the browser establishes a TCP (Transmission Control Protocol) connection with the server. For HTTPS, there is an additional step where the browser and server perform a TLS/SSL handshake to establish a secure connection.
HTTP Request:

The browser sends an HTTP request to the server, specifying the method (GET, POST, etc.), the path, and other headers. This request is sent to the server’s IP address obtained from the DNS resolution.
Server Processing:

The server processes the request, which may involve accessing a specific file or executing code. The server then generates an HTTP response containing the requested data, along with appropriate headers.
HTTP Response:

The server sends the HTTP response back to the browser. The response includes the requested data (HTML, CSS, JavaScript, images, etc.) and relevant metadata.
Rendering:

The browser receives the response and begins rendering the content. It parses the HTML to create the Document Object Model (DOM), processes CSS to create the CSS Object Model (CSSOM), and executes JavaScript to manipulate the DOM and CSSOM.
Displaying the Page:

The browser combines the DOM, CSSOM, and any additional resources (images, fonts, etc.) to display the fully rendered web page in the user’s browser window.
Rendering Updates:

As the user interacts with the page, the browser might fetch additional resources or execute JavaScript events, leading to dynamic updates. These updates are seamlessly reflected in the displayed content.
Caching:

Throughout this process, browsers use caching mechanisms to store certain resources locally. Cached resources can be reused to improve page load times, especially for frequently visited websites.
Understanding this sequence of steps helps in troubleshooting performance issues, optimizing web applications, and comprehending the intricacies of how web pages are loaded and displayed in a browser.

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31
Q

Describe the difference between SSR and CSR. Discuss the pros and cons.
-Are you familiar with static rendering?
-Rehydration?

A

Server-Side Rendering (SSR):

Rendering Location: In SSR, the rendering of the web page occurs on the server. The server generates the HTML for a page and sends the fully rendered content to the client.
Pros:
Improved Initial Load Time: Users get a fully rendered page in the initial request, improving perceived performance.
Search Engine Optimization (SEO): Search engines can crawl and index the content more effectively since the HTML is already populated.
Cons:
Slower Subsequent Interactions: Subsequent interactions may involve additional requests to the server, impacting performance.
Server Load: Server load can increase, especially in scenarios with a high number of concurrent users.
Client-Side Rendering (CSR):

Rendering Location: In CSR, the initial HTML is minimal, and the client-side JavaScript is responsible for rendering the content dynamically after the page loads.
Pros:
Faster Subsequent Interactions: Once the initial page loads, subsequent interactions can be faster as only data, not HTML, needs to be fetched.
Reduced Server Load: The server is less burdened during initial requests, making it potentially more scalable.
Cons:
Slower Initial Load Time: Users might experience a delay before the page becomes interactive since rendering happens on the client.
SEO Challenges: Traditional web crawlers may have difficulties indexing content since initial HTML is minimal.
Static Rendering:

Rendering Location: In static rendering, the HTML is generated at build time, and the same pre-rendered content is served to all users.
Pros:
Fastest Load Time: Static rendering provides the fastest load times as the HTML is pre-generated.
Cost-Effective: Reduced server load and improved performance can be cost-effective for serving static content.
Cons:
Limited Dynamic Content: Dynamic content, like personalized user data, may not be available at build time.
Build Time Overheads: The build process may take longer for larger websites with frequent updates.
Rehydration:

Definition: Rehydration is the process in CSR where the client-side JavaScript framework or library takes over the static HTML, adding interactivity and making the page fully functional.
Importance: Rehydration is crucial for CSR to ensure that the client-side JavaScript framework can take control seamlessly without causing inconsistencies or glitches.
Understanding these rendering approaches helps in choosing the right strategy based on project requirements and goals, balancing factors like initial load time, SEO, and dynamic content.

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32
Q

What is CSS selector specificity and how does it work?

A

Specificity is how the browser decides which CSS rule to apply when there are conflicting styles. It’s determined by the number of IDs, classes, and elements in a selector. More specific selectors override less specific ones. IDs have the highest specificity, followed by classes and elements. Inline styles trump everything.

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33
Q

What is the difference between “resetting” and “normalizing” CSS? Which would you choose, and why?

A

Resetting CSS eliminates default browser styles to start from a clean slate. Normalizing CSS preserves useful defaults but evens out inconsistencies between browsers. I’d choose normalization for a more consistent baseline while still keeping some defaults intact.

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34
Q

Describe Floats and how they work.

A

Certainly, floats are a CSS property used for layout. When an element is floated, it’s taken out of the normal document flow and positioned to the left or right within its containing element. This allows other elements to wrap around it. Floats were traditionally used for creating multi-column layouts, but flexbox and grid are more modern alternatives.

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35
Q

Describe z-index and how stacking context is formed.

A

z-index is a CSS property that controls the stacking order of elements along the z-axis. The higher the z-index, the closer an element is to the user.

A stacking context is formed when an element fulfills any of these conditions:

It has a z-index value other than auto.
It’s positioned with a value other than static (e.g., relative, absolute, fixed).
It’s a flex container with z-index other than auto.
It’s an element with opacity less than 1.
It’s a transform or perspective property with a value other than none.
Understanding stacking context helps in managing the visual order of overlapping elements.

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36
Q

Describe BFC (Block Formatting Context) and how it works.

A

A Block Formatting Context, or BFC, is a region in the visual CSS rendering of a web page where the layout of block-level boxes occurs. It ensures that block-level elements inside it are laid out in a specific way, avoiding certain layout issues.

BFC is formed under conditions like:

The root element of the document.
Floats (left or right).
Absolutely positioned elements.
Inline-blocks.
Table cells and table-caption elements.
Elements with overflow other than visible.
Understanding BFC is crucial for dealing with layout challenges and achieving consistent and predictable designs.

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37
Q

What are the various clearing techniques and which is appropriate for what context?

A

Clearing techniques are used to manage floats. The main ones are:

Clear Property:

Usage: Apply the clear property to an element to ensure it appears below any preceding floated elements.
Appropriate Context: Use it when you want to control the clearing behavior for a specific element.
clearfix Hack:

Usage: Adding a clearfix class to a container with floated children, often using the ::after pseudo-element to generate clearing content.
Appropriate Context: Handy when you want a quick fix for clearing floats without affecting other styles.
Overflow Property:

Usage: Apply overflow: auto or overflow: hidden to a container to clear floats.
Appropriate Context: Useful when you want a simple and effective way to contain floats within a specific element.
Flexbox and Grid:

Usage: Leveraging flexbox or grid layout to create a structured and controlled layout, avoiding common float-related issues.
Appropriate Context: Preferable for modern layouts where flexbox or grid can be used for overall structure and alignment.
Choosing the appropriate clearing technique depends on the specific needs of your layout and the level of control you require. Flexbox and grid are preferred for modern layouts, while traditional techniques like the clear property or overflow method are suitable for simpler scenarios.

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38
Q

How would you approach fixing browser-specific styling issues?

A

First, I’d identify the specific issue using browser developer tools. Then, I’d consider these approaches:

CSS Resets/Normalizations:

Use resets or normalizations to create a consistent baseline across browsers.
Feature Queries:

Employ feature queries (@supports) to apply styles conditionally based on browser support.
Vendor Prefixes:

Add vendor prefixes for properties that might need them (e.g., -webkit-, -moz-).
Polyfills:

Consider polyfills for missing features or functionality in older browsers.
Conditional Comments:

For IE-specific issues, use conditional comments to include IE-specific styles or scripts.
Testing and Debugging:

Regularly test and debug across different browsers to catch issues early.
Flexibility with Frameworks:

If using a CSS framework, leverage its features for cross-browser compatibility.
Community Resources:

Consult community forums, browser documentation, or compatibility tables for known issues and solutions.
Addressing browser-specific styling issues requires a combination of careful coding practices, testing, and leveraging tools and resources available in the developer community.

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39
Q

How do you serve your pages for feature-constrained browsers?
What techniques/processes do you use?

A

For feature-constrained browsers, I typically follow these techniques:

Progressive Enhancement:

Start with a solid foundation of HTML, CSS, and essential JavaScript. Enhance the experience for modern browsers with additional features.
Feature Detection:

Use feature detection libraries like Modernizr to identify and adapt to the capabilities of the user’s browser.
Responsive Design:

Implement responsive design principles to ensure that pages adapt to various screen sizes and device capabilities.
Graceful Degradation:

Plan for graceful degradation by providing a functional and accessible baseline experience for less capable browsers.
Polyfills:

Include polyfills for missing features in older browsers, ensuring that essential functionality is maintained.
Conditional Loading:

Use conditional loading to serve different assets or scripts based on browser capabilities.
Server-Side Rendering (SSR):

Employ server-side rendering for better performance on devices with limited processing power.
Content Delivery Networks (CDNs):

Utilize CDNs for serving assets, optimizing load times for users in various locations and on different devices.
By combining these techniques, I aim to create a resilient and accessible web experience that adapts to the diverse capabilities of users’ browsers and devices.

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40
Q

What are the different ways to visually hide content (and make it available only for screen readers)?

A

If you want to visually hide content while still making it available to screen readers, a common approach is to use CSS. You might set the position to absolute, give it a width and height of 1px, and use a large negative margin to push it off-screen.

Another way is to leverage ARIA attributes. You can use aria-hidden=”true” on an element to hide it from screen readers while keeping it visible on the page. This is useful for decorative elements that don’t contribute to the content’s meaning.

These techniques ensure a more inclusive experience, providing information to screen reader users without cluttering the visual interface for others.

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41
Q

Have you used or implemented media queries or mobile specific layouts/CSS?

A

Absolutely, I’ve extensively used media queries and implemented mobile-specific layouts in my projects. Media queries allow us to apply specific styles based on the characteristics of the device or viewport, like screen width, height, or device orientation.

Creating mobile-specific layouts involves designing and styling the interface to optimize the user experience on smaller screens. This often includes adjusting the size and spacing of elements, hiding or reorganizing certain content, and sometimes even changing the overall design structure. The goal is to ensure that the website looks and functions well across a variety of devices, from desktop monitors to smartphones and tablets.

Mobile-first design is a common approach, where the default styles are tailored for smaller screens, and media queries are used to enhance the layout for larger devices. This not only improves the user experience on mobile but also contributes to better overall performance by delivering only the necessary styles to each device.

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42
Q

Are you familiar with styling SVG?

A

Yes, I’m familiar with styling SVG (Scalable Vector Graphics). SVG is an XML-based format for describing vector graphics, and styling it involves using CSS (Cascading Style Sheets) to define the appearance of the SVG elements.

Here are some common ways to style SVG:

Inline Styling:

Apply styles directly within the SVG markup using the style attribute.
External Stylesheet:

Use an external CSS stylesheet to define styles for SVG elements.
Presentation Attributes:

SVG elements can have presentation attributes that directly define their appearance. These attributes can be used to set properties like fill, stroke, stroke-width, etc.
Class and ID:

Apply classes or IDs to SVG elements to reference them in CSS for styling.
CSS Selectors:

Utilize CSS selectors to target specific SVG elements or groups for styling.
Gradients and Patterns:

SVG supports gradients and patterns that can be used for more complex and dynamic fills.
Styling SVG is powerful and flexible, allowing for a wide range of visual effects. It’s essential to consider the unique properties of SVG, such as paths, strokes, and fills, when applying styles to ensure the desired appearance is achieved.

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43
Q

Can you give an example of an @media property other than screen?

A

Certainly! Besides the commonly used screen value for the @media rule, another example is print. The print value is used to apply styles specifically when a document is being printed. This allows you to create styles optimized for the printed page, such as adjusting font sizes, hiding unnecessary elements, or ensuring proper page breaks.

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44
Q

What are some of the “gotchas” for writing efficient CSS?

A

When crafting efficient CSS, it’s crucial to be cautious with the use of !important, as its overuse can lead to specificity challenges. Additionally, excessive nesting should be avoided, as it can result in overly specific styles that are hard to manage. Removing unused CSS and steering clear of large background images in stylesheets contributes to faster loading times. Mindful selection of font variants and weights helps prevent unnecessary delays in rendering. Be wary of global selectors (*) and consider the impact of their broad application. Shorthand properties, like margin and padding, enhance code readability. Minimizing the use of @import and leveraging CSS minification before deployment are practices that optimize performance.

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45
Q

What are the advantages/disadvantages of using CSS preprocessors?
Describe what you like and dislike about the CSS preprocessors you have used.

A

CSS preprocessors like Sass and Less bring efficiency to styling with features such as variables, mixins, and nested rules, promoting cleaner and more maintainable code. They enhance development speed and allow for the creation of modular, DRY styles. However, there are drawbacks, including the need for a compilation step and the potential for code bloat if features are overused. Teams must ensure familiarity with the chosen preprocessor and be mindful of the extra complexity in the development workflow.

Likes:
I appreciate the potential for improved code organization and readability that CSS preprocessors bring. Features like variables and mixins seem like powerful tools that could make styling more efficient. The idea of creating modular, reusable styles with less redundancy is appealing and could contribute to a more maintainable codebase.

Dislikes:
On the downside, the need for an additional compilation step in the workflow might introduce complexity, and I’d need to ensure that the team is comfortable with this extra layer. Also, there’s a concern about potential code bloat if the features are not used judiciously. Given these considerations, it would be important to weigh the benefits against the added complexity before deciding to adopt a preprocessor.

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46
Q

How would you implement a web design comp that uses non-standard fonts?

A

To implement a web design comp that uses non-standard fonts, I’d follow these steps. First, I’d choose a web font service like Google Fonts or Typekit and select the desired font. Then, I’d integrate the font into the project by linking the appropriate stylesheet in the HTML file. This ensures the font is loaded dynamically when the page loads.

In the CSS, I’d apply the chosen font to the relevant elements using the font-family property. It’s essential to provide fallback fonts in case the chosen font fails to load, ensuring a graceful degradation of the design. I’d also consider font-weight and font-style properties for variations.

Lastly, I’d optimize performance by using the font-display property to control how the font is displayed while it’s loading. For instance, using font-display: swap allows the browser to use a system font temporarily until the custom font is available.

This approach ensures a consistent and visually appealing design across different devices while considering performance and fallback scenarios.

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47
Q

Explain how a browser determines what elements match a CSS selector.

A

When a browser determines what elements match a CSS selector, it starts parsing the selector from right to left, checking if the rightmost element and its ancestors match the conditions specified. It then moves left, considering cascade and specificity, checking siblings and children along the way. The process involves traversing the document tree, accounting for pseudo-classes or pseudo-elements if present. Finally, the browser has a list of matched elements to which the specified styles will be applied. Understanding this process is crucial for writing efficient and specific selectors in CSS.

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48
Q

Describe pseudo-elements and discuss what they are used for.

A

Pseudo-elements in CSS, denoted by a double colon (::), allow styling specific parts of an element. Commonly used pseudo-elements include ::before and ::after, which create virtual elements before and after the content of the selected element. Pseudo-elements are used for decorative purposes, enabling the addition of content or styling to specific parts of an element without altering the actual HTML content. For example, ::before and ::after can be employed to insert decorative elements, such as icons or text, for enhanced visual design. Pseudo-elements provide a powerful way to manipulate the presentation of content without the need for additional HTML markup.

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49
Q

Explain your understanding of the box model and how you would tell the browser in CSS to render your layout in different box models.

A

The box model in CSS is like the blueprint for how elements are structured on a webpage. It considers an element as a box with content, padding, border, and margin. Now, if you want to tell the browser to handle this layout in different ways, you’d use the box-sizing property. The default is content-box, where the specified width and height only apply to the content, but if you want those dimensions to include padding and border, you’d go for border-box. It’s a handy way to simplify sizing calculations and ensure a more consistent layout.

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50
Q

What does * { box-sizing: border-box; } do? What are its advantages?

A

Applying * { box-sizing: border-box; } in CSS sets the box-sizing property to border-box for all elements on a webpage. This means that the specified width and height of an element include its padding and border, rather than only the content. The primary advantage of using box-sizing: border-box; globally is that it simplifies layout calculations. When you set a specific width for an element, you can be confident that it will include padding and border, making it easier to create consistent and predictable layouts. This can save time and reduce the complexity of managing spacing and sizing in a stylesheet, leading to more maintainable and efficient code.

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51
Q

What is the CSS display property and can you give a few examples of its use?

A

The CSS display property controls how an HTML element is shown on the page. For example, display: block; makes an element a block that starts on a new line, while display: inline; makes it inline within the content. There’s also display: none; to completely hide an element. Flexbox and Grid layouts come into play with display: flex; and display: grid;, offering powerful tools for creating flexible and grid-based layouts, respectively. It’s a go-to property for managing the structure and appearance of elements in CSS.

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52
Q

What is the difference between inline and inline-block?

A

The difference between inline and inline-block in CSS is in their layout behavior. Inline elements flow within the content, not starting on a new line and taking only as much width as necessary, while inline-block combines inline behavior with the ability to set width, height, and spacing, allowing for block-level styling within the inline flow.

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53
Q

What is the difference between the “nth-of-type()” and “nth-child()” selectors?

A

The difference between the “nth-of-type()” and “nth-child()” selectors in CSS lies in their scope of selection. The “nth-child()” selector targets elements based on their position among all children of the same parent, regardless of their element type. In contrast, the “nth-of-type()” selector specifically targets elements based on their position among siblings of the same type. So, “nth-child()” considers all children, while “nth-of-type()” focuses on elements of the same type within their parent.

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54
Q

What is the difference between a relative, fixed, absolute and statically positioned element?

A

In CSS, the position property has four main values. Static is the default, placing elements in the normal document flow. Relative lets you shift elements from their normal position. Absolute takes elements out of the flow, positioning them relative to the nearest positioned ancestor. Finally, Fixed removes elements from the flow and positions them relative to the browser window, making them stay fixed even when scrolling. Each value serves different layout purposes on a webpage.

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55
Q

What existing CSS frameworks have you used locally, or in production? How would you change/improve them?

A

I’ve mainly worked with Bootstrap in the past, and while it’s a solid framework, I’ve thought about a couple of improvements. One thing could be more straightforward customization options to break away from the typical Bootstrap appearance. Sometimes, it can be a bit recognizable. It’d be great if there were ways to easily tweak default styles without too much hassle. Also, having a more streamlined process to include only the components you need could help reduce unnecessary bloat in the final CSS. Improved documentation on advanced customization or theming would be a plus too, making it more versatile for different design requirements.

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56
Q

Can you explain the difference between coding a web site to be responsive versus using a mobile-first strategy?

A

Coding a website to be responsive means designing and implementing styles that adapt to various screen sizes and devices, ensuring a seamless user experience across desktops, tablets, and mobile phones. This often involves using media queries and flexible layouts.

On the other hand, a mobile-first strategy is a specific approach to responsive design. With a mobile-first strategy, you start designing and coding for mobile devices first and then progressively enhance the design for larger screens. This ensures that the core content and functionality are optimized for smaller screens, and as the screen size increases, additional styles or features are applied.

In essence, responsive design is a broader concept that encompasses various strategies, and mobile-first is one such strategy that prioritizes the mobile experience during development.

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57
Q

Have you used CSS Grid?

A

Yes, I’ve worked with CSS Grid. It’s a powerful layout system that simplifies the creation of complex, two-dimensional layouts in web design. With its ability to define both rows and columns, it provides a flexible and intuitive way to structure content on a webpage. I’ve found it particularly useful for building responsive layouts and aligning content in a more dynamic way than traditional methods like floats or flexbox.

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58
Q

Have you ever worked with retina graphics? If so, when and what techniques did you use?

A

I’ve had experience with retina graphics, and a neat solution I’ve often used is leveraging the ‘srcset’ attribute in HTML. This allows you to define multiple image sources with different resolutions and let the browser choose the most suitable one based on the user’s screen size. It’s a straightforward way to ensure images look sharp on both standard and high-density displays. Additionally, for icons, I’ve often leaned towards using SVG (Scalable Vector Graphics) whenever possible. SVGs are resolution-independent and perfect for maintaining crispness across various screen sizes and resolutions. It’s a handy combo – ‘srcset’ for images and SVG for icons – to keep things looking top-notch on all devices.

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59
Q

Is there any reason you’d want to use translate() instead of absolute positioning, or vice-versa? And why?

A

when deciding between translate() and absolute positioning in CSS, think about your goal. If you’re into smooth animations and transitions without impacting the normal document flow, go for translate(). It’s perfect for moving elements in a visually pleasing way. On the flip side, if you’re focusing on precise positioning within a layout structure, absolute positioning might be your go-to. Each has its sweet spot – translate() for smooth moves and absolute positioning for pinpoint layout control.

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60
Q

How is clearfix css property useful?

A

The clearfix CSS property isn’t an actual CSS property; rather, it’s a commonly used technique to address issues with clearing floated elements. When elements are floated, it can sometimes lead to layout problems, especially with their containing element not recognizing the height of the floated elements. To fix this, the clearfix technique is often applied by adding a pseudo-element with the clear: both; property to the container. This effectively clears the floated elements, ensuring that the container wraps around them and avoids layout issues. It’s a handy solution to maintain the expected layout when working with floated elements in CSS.

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61
Q

Can you explain the difference between px, em and rem as they relate to font sizing?

A

When it comes to font sizing in CSS, think of px as an absolute unit, giving you a fixed size. On the other hand, em is a relative unit, sizing the font relative to its parent. If the parent’s font size is 16px, 1em is 16px. Now, rem is also relative, but it’s relative to the root element’s (<html>) font size. So, 1rem is always 16px if the root font size is 16px, providing a consistent reference point across the document. Each has its role in handling font sizes based on different considerations.

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62
Q

Can you give an example of a pseudo class? Can you provide an example use case for a pseudo class?

A

A common pseudo-class in CSS is :hover. This pseudo-class is used to select and style an element when it’s being hovered over by the user.

A practical use case for :hover is creating interactive and visually appealing effects for buttons, links, or any elements that you want to respond to user interaction. It’s a great way to provide feedback and enhance the user experience on a website.

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63
Q

What is the difference between a block level element and an inline element. Can you provide examples of each type of element?

A

In CSS, block-level elements, like <div> or <p>, take up the full width, start on a new line, and stack vertically. They’re great for structural elements. On the flip side, inline elements, like <span> or <a>, only take up as much width as necessary, and they don’t force a new line. They’re handy for smaller, inline content like text or links. So, block-level elements give you that full-width, new-line treatment, while inline elements are more about fitting in with the text flow.</a></span>

64
Q

What is the difference between CSS Grid and Flexbox? When would you use one over the other?

A

CSS Grid and Flexbox are both layout tools in CSS, but they have different strengths. If I’m working on a one-dimensional layout, like aligning items along a row or column, I’d go for Flexbox. It’s great for simpler structures. Now, if I need to set up a two-dimensional layout with rows and columns, that’s where CSS Grid shines. It gives more precise control over both dimensions and is perfect for more complex layouts. So, it really depends on the layout needs of the project – Flexbox for simpler, one-dimensional stuff, and CSS Grid for more intricate, two-dimensional designs.

65
Q

What is the difference between fixed, fluid and responsive layouts?

A

a fixed layout is like a set width that doesn’t change, a bit inflexible. Fluid layouts use percentages, adapting to different screen sizes, but might not optimize for all devices. Now, responsive layouts, that’s the sweet spot. They adjust smartly, using flexible grids and media queries, making sure the design looks great on any device. It’s about finding that balance between flexibility and targeted adjustments for the best user experience.

66
Q

What does a doctype do?

A

a doctype, short for Document Type Declaration, sets the rules for the HTML parser about how to interpret the document. It helps browsers render the page correctly by defining the HTML version being used. Essentially, it ensures consistency in how browsers interpret and display the content

67
Q

How do you serve a page with content in multiple languages?

A

To handle content in multiple languages, I’d set the lang attribute in the HTML tag to define the primary language for the entire page. Within the content, I’d use elements with the lang attribute again to specify the language for specific sections. Managing translations, I might use language files or a content management system. Additionally, considering user preferences or location, I’d implement language-switching functionality. It’s all about creating a seamless and inclusive experience for users regardless of their language.

68
Q

What kind of things must you be wary of when designing or developing for multilingual sites?

A

When working on multilingual sites, it’s crucial to be mindful of various factors. One key consideration is text expansion or contraction – different languages might have varying lengths, potentially affecting layout and design. Also, watch out for font choices, ensuring they support all characters across languages. Another challenge is maintaining consistency in terminology and style across translations. Dynamic content, like date formats or currency symbols, must adapt appropriately. And, of course, testing across different languages and devices is essential to catch any unexpected issues. It’s a balancing act to ensure a cohesive and user-friendly experience across diverse linguistic contexts.

69
Q

What are data- attributes good for?

A

data-attributes are handy in HTML for storing custom data private to the page or application. They provide a way to attach extra information to elements without affecting the rendering or behavior. It’s great for JavaScript to grab and manipulate data, making the HTML more semantically meaningful for scripting purposes. For instance, you might use a data-attribute to store specific data like IDs or configuration details, giving a clean separation between content and functionality.

70
Q

Consider HTML5 as an open web platform. What are the building blocks of HTML5?

A

It introduces semantic elements like <article>, <section>, and <header>, enhancing the structure of web documents. The <canvas> element allows for dynamic graphics and animations, while the <audio> and <video> elements support native multimedia embedding. Form elements like <input></input> have new attributes and types for improved user interaction, and the introduction of local storage via Web Storage (localStorage) provides client-side data persistence. Overall, HTML5 enhances the web by providing a more feature-rich and structured environment for building modern web applications.</video></audio></canvas>

71
Q

Describe the difference between a cookie, sessionStorage and localStorage.

A

cookies, sessionStorage, and localStorage are all ways to store data on the client side, but they have some key differences.

Cookies:

Limited to about 4KB of data.
Sent with every HTTP request, impacting performance.
Has an expiration time, either session-based or set explicitly.
sessionStorage:

Allows for the storage of data for the duration of the page session.
Limited to the lifetime of the page session, so the data is lost when the tab or window is closed.
Provides a more secure alternative to cookies for session-based data storage.
localStorage:

Similar to sessionStorage but persists even when the browser is closed and reopened.
Has a larger storage capacity compared to cookies and sessionStorage.
Considered a good option for long-term, client-side storage needs.
Choosing among them depends on the specific use case – cookies for smaller, temporary data, sessionStorage for session-based needs, and localStorage for longer-term storage requirements.

72
Q

Describe the difference between

, 
 and 
.
A
<script>
loads and executes the script synchronously, potentially delaying the rendering. Now, <script async> is like telling the browser to keep downloading other resources while it fetches the script. It doesn't wait for the script to finish downloading before moving on. <script defer>, on the other hand, defers script execution until after the HTML parsing is complete. So, it's loaded in the background but won't block rendering. Async is great for scripts that don't rely on the page structure, while defer is useful when script order matters but you want it to load in the background.
</script>
73
Q

Why is it generally a good idea to position CSS <link></link>s between <head></head> and JS

s just before </body>? Do you know any exceptions?
A

Placing CSS <link></link> elements in the <head> allows styles to load early, preventing a flash of unstyled content. Meanwhile, placing JS

 elements just before </body> ensures they don't block rendering, improving page load speed. This way, the page content can load first, and scripts can do their thing later. Exceptions might include critical CSS, which could be inlined in the <head> to minimize render-blocking, or situations where specific script dependencies require early loading. It's about finding the right balance between performance and functionality.
74
Q

What is progressive rendering?

A

Progressive rendering is like serving a webpage in stages, gradually improving the user experience. Instead of waiting for the entire page to load, the browser renders and displays content as it arrives. This means users see something meaningful sooner, even if it’s not the complete page. Images might start as placeholders and gradually load, text appears, and interactions become available. It’s a user-centric approach, ensuring a smoother and more engaging experience, especially on slower network connections.

75
Q

Why you would use a srcset attribute in an image tag? Explain the process the browser uses when evaluating the content of this attribute.

A

You’d use the srcset attribute in an image tag to provide the browser with a set of image sources with different resolutions or sizes. This helps in delivering the most appropriate image based on the user’s device capabilities, screen size, and network conditions. The browser evaluates the srcset content, considering the pixel density descriptors (like 1x, 2x) and width descriptors (like 320w, 480w). It then selects the most suitable image source to download and display. This ensures optimal image quality and performance, as the browser fetches an image that matches the user’s device characteristics, preventing unnecessary data and bandwidth usage.

76
Q

Have you used different HTML templating languages before?

A

Yes, Pug (formerly Jade), ERB, Slim, Handlebars, Jinja, Liquid, and EJS just to name a few. In my opinion, they are more or less the same and provide similar functionality of escaping content and helpful filters for manipulating the data to be displayed. Most templating engines will also allow you to inject your own filters in the event you need custom processing before display.

77
Q

What is the difference between canvas and svg?

A

think of <canvas> as a blank canvas where you draw pixel-based graphics using JavaScript. It's great for dynamic and complex visualizations like games. On the other hand, <svg> is more like a vector graphics language. It uses XML to describe shapes and paths, providing a scalable and flexible way to create graphics. SVG is better for static images or graphics that might need to be resized without losing quality. While <canvas> is pixel-based and controlled with scripts, <svg> is a markup language for defining scalable vector graphics directly in the HTML. Each has its strengths depending on the use case.</svg></canvas></svg></canvas>

78
Q

What are empty elements in HTML ?

A

Empty elements in HTML are those that don’t have any content or text between the opening and closing tags. They are self-closing tags, meaning the closing tag is omitted. Common examples include the <img></img> tag for images, <br></br> for line breaks, and <input></input> for input fields. These elements serve specific purposes and don’t require additional content. They are written in a self-closing format, like <img></img>, making the HTML more concise.

79
Q

Explain event delegation.

A

Event delegation is a technique involving adding event listeners to a parent element instead of adding them to the descendant elements. The listener will fire whenever the event is triggered on the descendant elements due to event bubbling up the DOM. The benefits of this technique are:

Memory footprint goes down because only one single handler is needed on the parent element, rather than having to attach event handlers on each descendant.
There is no need to unbind the handler from elements that are removed and to bind the event for new elements.

80
Q

Explain how this works in JavaScript.
Can you give an example of one of the ways that working with this has changed in ES6?

A

In JavaScript, the this keyword refers to the object it belongs to in a given context. The context can vary based on how a function is invoked. In a method, this points to the object the method is called on. In a regular function, this depends on how the function is called – if it’s a standalone function, it refers to the global object (like window in browsers), but in strict mode, it’s undefined. Arrow functions, on the other hand, inherit this from the enclosing scope and don’t have their own this binding. So, understanding the context of a function call is key to grasping how this behaves in JavaScript.

n ES6, the introduction of arrow functions has influenced how the this keyword behaves. In traditional function expressions, this is dynamically scoped based on how the function is called, which can lead to unexpected behavior. Arrow functions, however, capture the this value from their lexical scope. This means that when using arrow functions as methods on objects or within other functions, this retains the value from the surrounding context, eliminating the need for workarounds like .bind(this) or creating aliases for this. It simplifies and clarifies the code, making it more concise and readable.

81
Q

Explain how prototypal inheritance works.

A

Prototypal inheritance in JavaScript is like inheriting characteristics from a prototype object. Every object in JavaScript has a prototype, which is essentially another object that it inherits properties and methods from. When you access a property or method on an object, JavaScript first looks for it in the object itself. If it doesn’t find it, it checks the object’s prototype, and this process continues up the prototype chain until the property or method is found or the end of the chain is reached. If it’s not found anywhere, the result is undefined. This mechanism allows objects to inherit and share functionality, creating a more efficient and modular code structure.

82
Q

What is the difference between a variable that is: null, undefined or undeclared? How would you go about checking for any of these states?

A

null: It’s a value that represents the intentional absence of any object value. It’s a valid assignment to a variable, indicating that the variable has no value or no object reference.

undefined: It typically signifies an uninitialized variable, meaning a variable has been declared but has not been assigned a value. It’s also the default value of function parameters that are not provided.

Undeclared: Refers to a variable that has been used without being declared with var, let, or const. Attempting to access an undeclared variable results in a reference error.

So, null is a deliberate absence of value, undefined is typically unintentional, and undeclared refers to using a variable that hasn’t been declared at all.

To check if a variable is null, you can use a strict equality check (===) against null. For example: if (myVar === null)

To check if a variable is undefined, you can use a strict equality check against undefined. For example: if (myVar === undefined)

To check if a variable is undeclared, you can use a combination of typeof and strict equality check against undefined. For example: if (typeof myVar === ‘undefined’)

It’s important to note that when checking for undefined, it’s generally recommended to use a strict equality check (===) to avoid unexpected behavior due to type coercion.

83
Q

What is a closure, and how/why would you use one?

A

A closure in JavaScript is like a backpack for variables, allowing a function to retain access to the variables from its outer (enclosing) scope even after that scope has finished executing. It essentially “closes over” those variables. Closures are created when a function is defined inside another function, forming a lexical scope chain.

You might use closures to:

Create private variables: Variables declared in an outer function are not accessible from outside, but inner functions within that scope can still access them, creating a way to achieve encapsulation.
Maintain state: Closures allow functions to remember and access the variables of the outer function even after the outer function has completed its execution. This is useful for maintaining state between function calls.
For example, you might use a closure to create a counter that is not directly accessible from outside the function, providing a form of data hiding and encapsulation.

84
Q

What language constructions do you use for iterating over object properties and array items?

A

For iterating over object properties, you can use a for…in loop in JavaScript

for (let key in myObject) {
if (myObject.hasOwnProperty(key)) {
// Access myObject[key] here
}
}

The hasOwnProperty check ensures that only the object’s own properties are iterated, excluding inherited ones.

For iterating over array items, you can use a for loop or the array iteration methods like forEach, map, filter, and others. Here’s an example using forEach:

myArray.forEach(function(item) {
// Access array item here
});

These constructs provide flexibility and control over the iteration process, allowing you to perform various actions on each property or item.

85
Q

Can you describe the main difference between the Array.forEach() loop and Array.map() methods and why you would pick one versus the other?

A

Both forEach and map are array iteration methods in JavaScript, but they serve different purposes.

forEach: It’s used when you want to iterate over each item in an array and perform some operation or side effect for each item. However, forEach doesn’t create a new array; it simply applies a function to each element in the existing array.

map: It’s used when you want to transform each item in an array and create a new array with the results of those transformations. It returns a new array of the same length as the original, where each element is the result of applying the provided function to the corresponding element of the original array.

So, you would choose forEach when you want to perform some operation for each item in the array without creating a new array. On the other hand, you would use map when you want to transform each item and create a new array with the results of those transformations.

86
Q

What is a typical use case for anonymous functions?

A

Anonymous functions, or function expressions, are commonly used in scenarios where a function is needed for a specific task and doesn’t require a name. For example, in situations like immediately invoked function expressions (IIFE), callback functions, or inline functions used briefly within code blocks. They’re practical for cases where a function is short-lived and doesn’t need to be referenced elsewhere, promoting a more concise and localized approach to coding.

87
Q

What is the difference between host objects and native objects?

A

Host objects and native objects refer to two different categories of objects in the context of JavaScript.

Host Objects: These are objects provided by the environment in which JavaScript is executed, like the browser or Node.js environment. Examples include the window object in a browser or the global object in Node.js. Host objects can vary between different environments.

Native Objects: These are objects that are part of the JavaScript language specification itself, such as Array, Object, String, and Function. Native objects are consistent across all JavaScript environments.

In essence, the key difference lies in their origin: host objects come from the hosting environment, while native objects are inherent to the JavaScript language.

88
Q

Explain the difference between: function Person(){}, var person = Person(), and var person = new Person()?

A

The differences between function Person(){}, var person = Person(), and var person = new Person() revolve around how the Person function is invoked.

function Person(){}: This declares a function named Person. It doesn’t create an instance of the function; it’s just a function declaration.

var person = Person();: This calls the Person function, but if Person doesn’t explicitly return a value, person will be assigned undefined. This is a regular function invocation.

var person = new Person();: This creates a new instance of the Person function using the new keyword. It invokes the function as a constructor and assigns the resulting object to person. The new keyword ensures that the Person function acts as a constructor, creating and returning a new object.

In summary, the first one is a function declaration, the second is a regular function invocation, and the third is creating a new object instance using the new keyword.

89
Q

Explain the differences on the usage of foo between function foo() {} and var foo = function() {}

A

The differences between function foo() {} and var foo = function() {} lie in how they are defined and when they are hoisted.

function foo() {}: This is a function declaration. It is hoisted to the top of its scope, meaning you can call foo() even before the line where it’s declared.

var foo = function() {}: This is a function expression assigned to a variable. The variable declaration (var foo) is hoisted, but the assignment (= function() {}) is not. You can only call foo() after the line where it’s assigned.

In practical terms, the key difference is the hoisting behavior. If you need to use the function before its declaration, choose the function declaration (function foo() {}). If the order doesn’t matter, and you want to assign a function to a variable, use the function expression (var foo = function() {}).

90
Q

Can you explain what Function.call and Function.apply do? What is the notable difference between the two?

A

oth Function.call and Function.apply are methods in JavaScript that allow you to invoke a function with a specified this value and arguments.

Function.call(thisArg, arg1, arg2, …): This method invokes the function with a specified this value and individual arguments. The first argument (thisArg) is the value to be passed as the this parameter to the function, and subsequent arguments are passed as individual parameters.

Example: myFunction.call(obj, arg1, arg2)

Function.apply(thisArg, [arg1, arg2, …]): This method is similar to call, but it takes an array of arguments as its second parameter. The first argument is still the this value.

Example: myFunction.apply(obj, [arg1, arg2])

The notable difference is how arguments are passed. With call, you pass arguments individually, while with apply, you pass them as an array. The choice between them depends on how your function is designed to receive arguments. If you have an array of arguments or the number of arguments is dynamic, apply can be more convenient. Otherwise, call is commonly used.

91
Q

Explain Function.prototype.bind.

A

Function.prototype.bind is a method in JavaScript that creates a new function with a specified this value. It’s useful when you want to set the context for a function without immediately invoking it. This method returns a new function, allowing you to pass it around or use it later. It’s commonly used to ensure that a function is called with a specific context, which is helpful in scenarios like event handlers or when passing functions as callbacks.

92
Q

What is the difference between feature detection, feature inference, and using the UA string?

A

In front-end development, these terms relate to different approaches for handling browser capabilities:

Feature Detection: This involves checking if a particular feature or property is supported by the current browser. It’s a robust method as it directly tests for the capability rather than making assumptions based on browser identity.

Feature Inference: This involves making assumptions about a browser’s capabilities based on the presence of other features. It’s less reliable than feature detection because it relies on the assumption that certain features typically coexist.

Using the UA String (User-Agent): This involves parsing the User-Agent string sent by the browser to the server. It’s the least recommended approach as the User-Agent string can be manipulated, and it doesn’t directly indicate the browser’s capabilities.

In summary, feature detection is the preferred method for reliability, feature inference makes assumptions based on observed correlations, and using the UA string is discouraged due to its lack of accuracy and potential for manipulation.

93
Q

Explain “hoisting”.

A

Hoisting in JavaScript refers to the behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase, before the code is executed. This means that you can use a variable or call a function before it’s declared in the code. However, it’s important to note that only the declarations are hoisted, not the initializations.

For example, if you have a variable declaration var x = 5;, during hoisting, the interpreter will move the declaration (var x;) to the top of its scope. However, the assignment (= 5) will remain in its original position.

Understanding hoisting is crucial for writing predictable JavaScript code, especially when it comes to variable and function declarations in different parts of your code.

94
Q

What is type coercion? What are common pitfalls of relying on type coercion in JavaScript code?

A

Type coercion in JavaScript refers to the automatic conversion of values from one data type to another. This happens when an operation involves two values of different types. JavaScript will attempt to convert one or both values to a common type before performing the operation.

Common pitfalls of relying on type coercion include:

Unexpected Results: Type coercion can lead to unexpected or implicit conversions, making the code behavior less apparent.

Loss of Precision: Coercion may result in loss of precision or unintended changes to the values, especially when dealing with numbers and strings.

Implicit String Conversions: Concatenating a string and a non-string value can lead to unintended string conversions. This is particularly common when using the + operator.

Loose Equality Comparisons: Using loose equality (==) can lead to unexpected results due to type coercion. It’s often safer to use strict equality (===) to avoid unintended type conversions.

To write more robust and predictable code, it’s advisable to be explicit about type conversions when necessary and to use strict equality for comparisons. Understanding how type coercion works can help developers avoid common pitfalls in JavaScript code.

95
Q

Describe event bubbling.

A

Event bubbling is a phase in the event propagation model in browsers, where an event triggered on a particular element will first be captured by the innermost element and then propagate up through its ancestors in the DOM hierarchy. This allows parent elements to become aware of events that occurred on their descendants.

In other words, during the bubbling phase, the event starts from the target element and moves up the DOM tree until it reaches the root element. This mechanism provides an opportunity for multiple elements in the hierarchy to respond to the same event.

Understanding event bubbling is crucial for handling events in a hierarchical structure, and developers can leverage it to efficiently manage event delegation and handle events at higher levels in the DOM tree rather than attaching event listeners to every individual element.

96
Q

Describe event capturing

A

Event capturing is the initial phase in the event propagation model of browsers. During this phase, an event travels from the root of the DOM hierarchy down to the target element. It’s the opposite of event bubbling, which occurs afterward.

In event capturing, the browser captures the event at the outermost ancestor and then descends through the DOM hierarchy, checking for event listeners on each level. This provides an opportunity for elements higher in the hierarchy to intercept and handle the event before it reaches the target element.

While event capturing is less commonly used than event bubbling, it can be valuable in certain scenarios where you want to handle an event at a higher level in the DOM tree before it reaches the actual target element. However, for most cases, event bubbling is the more widely used and convenient approach.

97
Q

What is the difference between an “attribute” and a “property”?

A

Attribute: In HTML, attributes provide additional information about an HTML element and are always present in the HTML source code. Attributes are part of the markup and are used to define properties or settings for elements. They are accessed in JavaScript using the getAttribute method.

Example: <img></img>. Here, src and alt are attributes of the img element.

Property: Properties are features or values associated with a JavaScript object, including HTML elements. They can be dynamically changed during runtime and represent the current state of the element. In JavaScript, properties are accessed directly through the DOM.

Example: var image = document.getElementById(‘exampleImage’);
var source = image.src;. Here, src is a property of the img element.

In summary, attributes are part of the HTML markup, while properties are part of the live, dynamic representation of the HTML element in the DOM accessible through JavaScript.

98
Q

What are the pros and cons of extending built-in JavaScript objects?

A

Extending built-in JavaScript objects can be a powerful technique, but it comes with both advantages and drawbacks.

Pros:

Functionality Extension: You can add custom methods or properties to built-in objects, enhancing their functionality. This can lead to more expressive and readable code.

Consistency: By extending built-in objects, you can ensure that the custom functionality is consistent across your codebase, promoting a unified approach.

Convenience: Custom methods added to built-in objects can make code more concise and convenient to write.

Cons:

Global Scope Impact: Extending built-in objects affects all instances of those objects globally, which can lead to unexpected behavior or conflicts if not carefully managed.

Compatibility Issues: Future updates to JavaScript or libraries may introduce methods or properties with the same names as your extensions, causing compatibility issues.

Readability Concerns: Extending built-in objects can make code less readable for developers who are not aware of the extensions, leading to confusion.

Maintenance Challenges: Code maintainability can become challenging as the project grows, especially when multiple developers are involved. Unexpected interactions between extensions can arise.

In general, it’s recommended to use caution when extending built-in objects and consider alternative approaches, such as creating utility functions or using prototypes, to minimize potential downsides. If you decide to extend built-in objects, document your extensions clearly and be mindful of the impact on the global scope.

99
Q

What is the difference between == and ===?

A

The == and === operators in JavaScript are used for equality comparisons, but they behave differently in terms of type coercion.

== (Loose Equality): This operator performs type coercion, meaning it tries to convert the operands to the same type before making the comparison. For example, ‘5’ == 5 would evaluate to true because the string is coerced into a number.

=== (Strict Equality): This operator does not perform type coercion. It checks both the value and the type of the operands. For example, ‘5’ === 5 would evaluate to false because the types are different.

In general, it’s recommended to use === (strict equality) because it avoids unexpected type coercion and ensures a more predictable comparison. Using == (loose equality) can lead to subtle bugs and is often considered error-prone.

100
Q

Explain the same-origin policy with regards to JavaScript.

A

The Same-Origin Policy is a security feature implemented by web browsers that restricts web pages from making requests to a different origin (domain, protocol, or port) than the one that served the original web page. This policy is enforced by browsers to prevent potentially malicious actions, such as cross-site request forgery (CSRF) and cross-site scripting (XSS) attacks.

In the context of JavaScript, the Same-Origin Policy applies to XMLHttpRequests, Fetch API, and other mechanisms that involve making network requests. JavaScript code running in a web page can only make requests to the same origin from which the page originated. Attempts to make requests to a different origin will be blocked by the browser.

To work around this limitation, web developers can use techniques such as JSONP (JSON with Padding), Cross-Origin Resource Sharing (CORS), or utilize server-side proxies to make requests to different origins. These methods allow for controlled and secure cross-origin communication while adhering to the security principles of the Same-Origin Policy.

101
Q

Why is it called a Ternary operator, what does the word “Ternary” indicate?

A

The term “ternary” in the context of the ternary operator refers to its three operands or components. The ternary operator is the only JavaScript operator that takes three operands. It’s often referred to as the “conditional operator” or the “ternary conditional operator. The use of three components (condition, expr1, and expr2) is what makes it a ternary operator.

102
Q

What is strict mode? What are some of the advantages/disadvantages of using it?

A

Strict mode is a feature in JavaScript that helps catch common coding errors and enforces stricter parsing and error-handling rules. The advantages include error prevention, improved security by disallowing certain error-prone features, and more predictable behavior. However, it might introduce compatibility concerns with older code and libraries, and there’s a learning curve for developers adjusting to its stricter rules. Overall, the benefits in terms of code reliability outweigh the challenges.

103
Q

What are some of the advantages/disadvantages of writing JavaScript code in a language that compiles to JavaScript?

A

Writing JavaScript code in a language that compiles to JavaScript, like TypeScript or Babel, has advantages such as improved maintainability, enhanced developer tooling, and the ability to use modern language features before they are supported natively. However, it adds a compilation step, potentially impacting build times. Additionally, there may be a learning curve for developers new to the language extension. The advantages often outweigh the disadvantages, especially in large projects where strong typing and advanced language features contribute to code quality and maintainability.

104
Q

What tools and techniques do you use debugging JavaScript code?

A

For debugging JavaScript code, I primarily rely on browser developer tools, like Chrome DevTools. I use breakpoints, console.log statements, and the interactive console for quick checks. Additionally, I leverage features like step-by-step execution, watch expressions, and source maps for a more in-depth analysis. Occasionally, I turn to tools like ESLint for static code analysis to catch potential issues early. Debugging is often an iterative process, combining these techniques to identify and fix issues efficiently.

105
Q

Explain the difference between mutable and immutable objects.
What is an example of an immutable object in JavaScript?
What are the pros and cons of immutability?
How can you achieve immutability in your own code?

A

Mutable objects in JavaScript can be modified after their creation, while immutable objects cannot be changed once created. An example of an immutable object is a string—once a string is created, its content cannot be altered.

The pros of immutability include enhanced predictability, easier debugging, and simplified state management, leading to more reliable code. However, immutability can result in increased memory usage, as new objects are created instead of modifying existing ones.

To achieve immutability, one can use techniques like Object.freeze for shallow immutability or libraries like Immutable.js for deep immutability. It involves creating new objects or arrays instead of modifying existing ones to ensure that the original data remains unchanged. This approach promotes a more functional programming style in JavaScript.

106
Q

Explain the difference between synchronous and asynchronous functions.

A

Synchronous functions in JavaScript execute sequentially, blocking the execution of the program until the function completes. Asynchronous functions, on the other hand, allow other tasks to proceed while waiting for an operation to finish. Asynchronous functions often involve callbacks, promises, or async/await syntax to handle asynchronous behavior.

For example, a synchronous function might execute a time-consuming task and pause the entire program until it’s done, while an asynchronous function would initiate the task and allow the program to continue with other operations, notifying when the task is finished. Asynchronous functions are crucial for handling operations like network requests or file I/O without freezing the entire application.

107
Q

What is event loop?
What is the difference between call stack and task queue?

A

The event loop is a fundamental concept in JavaScript’s concurrency model. It continuously checks the call stack and the task queue, ensuring that the execution of code remains non-blocking and efficient.

The call stack is a data structure that keeps track of function calls in the program. When a function is called, it is added to the top of the stack, and when it completes, it is removed. The event loop monitors the call stack.

The task queue is a queue data structure that holds callback functions and events. When an asynchronous operation is completed, its callback function is placed in the task queue.

The event loop constantly checks if the call stack is empty. If it is, it takes the first callback from the task queue and pushes it onto the call stack for execution. This process ensures that asynchronous operations don’t block the main thread and allows for non-blocking, concurrent JavaScript execution.

108
Q

What are the differences between variables created using let, var or const?

A

let, var, and const are used to declare variables in JavaScript. The key differences lie in their scope, hoisting behavior, and reassignment capabilities. let and const have block scope, var has function scope. let and const are hoisted but not initialized until their declaration, whereas var is hoisted and initialized with undefined. const variables cannot be reassigned, let and var can. Choosing between them depends on the desired scope and whether the variable will be reassigned.

109
Q

What are the differences between ES6 class and ES5 function constructors?

A

ES6 classes and ES5 function constructors are both used for object-oriented programming in JavaScript, but they have syntactic and behavioral differences. ES6 classes provide a more concise syntax for defining constructor functions and methods, with the class keyword and the constructor method. They also support class inheritance using the extends keyword. ES5 function constructors use a traditional function to create objects, relying on prototypes for inheritance. The ES6 class syntax is considered more readable and closer to other programming languages, while ES5 function constructors are more verbose. Both achieve similar functionality, but ES6 classes offer a cleaner and more modern approach.

110
Q

Can you offer a use case for the new arrow => function syntax? How does this new syntax differ from other functions?

A

The arrow (=>) function syntax in JavaScript is particularly useful for concise anonymous functions and for maintaining the lexical context of this. One common use case is in functions like array methods or callback functions where a short, straightforward syntax is beneficial. The arrow function automatically captures the surrounding this value, preventing the common issue of losing context in traditional function expressions. The arrow function also has a more concise syntax, omitting the need for the function keyword and curly braces for single-line expressions. This makes the code cleaner and often more readable.

111
Q

What advantage is there for using the arrow syntax for a method in a constructor?

A

Using the arrow syntax for a method in a constructor can be advantageous when you want the method to inherit the lexical scope of the constructor itself. Arrow functions don’t have their own this context; instead, they inherit it from the enclosing scope. In the context of a constructor, this means that the arrow function method will share the same this as the constructor, avoiding potential issues with traditional function expressions where this might refer to something else when used within a method. This can lead to cleaner and more predictable code, especially in scenarios where maintaining the correct context is crucial, such as in event handlers or callback functions.

112
Q

What is the definition of a higher-order function?

A

A higher-order function is a function that takes one or more functions as arguments or returns a function as its result. In simpler terms, it either accepts functions as parameters or outputs functions. Higher-order functions are a fundamental concept in functional programming and provide a powerful way to abstract and compose code. Examples of higher-order functions in JavaScript include map, filter, and reduce, which take functions as arguments to operate on arrays. These functions enable a more declarative and concise style of programming.

113
Q

Can you give an example for destructuring an object or an array?

A

Certainly! Destructuring in JavaScript allows you to extract values from objects or arrays and assign them to variables in a concise way.

Array Destructuring:

// Example with an array
const numbers = [1, 2, 3];
const [a, b, c] = numbers;
console.log(a); // 1
console.log(b); // 2
console.log(c); // 3
Object Destructuring:

// Example with an object
const person = { name: ‘Emily’, age: 30 };
const { name, age } = person;
console.log(name); // ‘Emily’
console.log(age); // 30
In these examples, destructuring simplifies the process of extracting values from arrays or objects and assigning them to variables. It’s a concise and expressive feature in JavaScript.

114
Q

Can you give an example of generating a string with ES6 Template Literals?

A

ES6 Template Literals provide a convenient way to generate strings with variables or expressions embedded in them using backticks (`).

// Example with variables
const name = ‘Emily’;
const age = 30;

const greeting = Hello, my name is ${name} and I'm ${age} years old.;
console.log(greeting);
// Output: Hello, my name is Emily and I’m 30 years old.
In this example, the ${} syntax allows you to embed variables or expressions within the string. This makes it more readable and avoids the need for concatenation or complex escaping, providing a cleaner way to generate strings.

115
Q

Can you give an example of a curry function and why this syntax offers an advantage?

A

Currying is a technique in functional programming where a function with multiple arguments is transformed into a sequence of functions, each taking a single argument. This can be achieved in JavaScript using closures.

Here’s an example of a simple curry function:

// Curry function
const curry = (fn) => {
return function curried(…args) {
if (args.length >= fn.length) {
return fn.apply(this, args);
} else {
return function (…moreArgs) {
return curried.apply(this, args.concat(moreArgs));
};
}
};
};

// Example usage
const add = (a, b, c) => a + b + c;
const curriedAdd = curry(add);

console.log(curriedAdd(1)(2)(3)); // Output: 6
console.log(curriedAdd(1, 2)(3)); // Output: 6
console.log(curriedAdd(1)(2, 3)); // Output: 6
The advantage of curry functions lies in partial application and creating more reusable and composable functions. You can gradually apply arguments, creating new functions along the way. This allows for better code organization, flexibility, and the ability to create specialized functions from a more general one.

116
Q

What are the benefits of using spread syntax and how is it different from rest syntax?

A

Spread syntax is beneficial for creating copies of arrays or objects, merging arrays, and passing array elements as function arguments. It spreads elements or properties. Rest syntax, on the other hand, is useful in function parameters to gather remaining arguments into a single array. It’s about collecting. So, spread is about spreading things out, while rest is about gathering things together, especially in function parameters.

117
Q

How can you share code between files?

A

Code sharing between files in JavaScript can be achieved through module systems. Common methods include using CommonJS (require/module.exports), ES6 modules (import/export), or other module systems like AMD. These approaches enable you to break code into modular pieces, encapsulating functionality and making it reusable across different files. This promotes a more organized and maintainable codebase. Choose the module system that aligns with your project’s requirements and the environment it runs in.

118
Q

Why you might want to create static class members?

A

Static class members are useful for properties or methods that are associated with a class itself rather than instances of the class. They are shared across all instances and can be accessed without creating an instance of the class. This is beneficial for utility functions, constants, or properties that don’t depend on specific instance data. Using static members helps avoid unnecessary duplication of information and promotes cleaner, more efficient code by associating elements directly with the class itself rather than instances.

119
Q

What is the difference between while and do-while loops in JavaScript?

A

The primary difference between while and do-while loops in JavaScript lies in when the loop condition is evaluated.

In a while loop, the condition is checked before the loop body is executed. If the condition is initially false, the loop body will never be executed.

In a do-while loop, the loop body is executed at least once before the condition is checked. This guarantees that the loop body runs at least once, even if the condition is initially false.

In summary, the key distinction is the timing of the condition evaluation: while checks the condition before executing the loop, while do-while checks the condition after executing the loop body.

120
Q

What is a promise? Where and how would you use promise?

A

A promise in JavaScript is an object representing the eventual completion or failure of an asynchronous operation. It is used for handling asynchronous operations like data fetching, file reading, or any operation that takes time to complete. A promise can be in one of three states: pending, resolved (fulfilled), or rejected.

Promises are useful when working with asynchronous code to improve readability and handle the complexity of callbacks. They provide a cleaner alternative to callback functions, making it easier to reason about and chain asynchronous operations. Promises are commonly used with functions that return data asynchronously, such as AJAX requests or reading files, allowing you to handle the result or error in a more structured and sequential manner.

121
Q

Discuss how you might use Object Oriented Programming principles when coding with JavaScript.

A

Object-Oriented Programming (OOP) principles can be applied in JavaScript to create more organized, modular, and reusable code. Here’s how you might use OOP principles in JavaScript:

Encapsulation:

Encapsulate related properties and methods within objects to group functionality.
Use closures to create private variables and methods.
Inheritance:

Use prototypal inheritance to share properties and methods among objects.
Create a prototype chain to allow objects to inherit from other objects.
Polymorphism:

Leverage the ability of objects to use the same interface (method or property name) but exhibit different behaviors.
Abstraction:

Abstract common features into classes or object prototypes.
Hide complex implementation details, exposing only what is necessary.
Classes and Constructors:

Use constructor functions or ES6 classes to create blueprints for objects.
Organize code into classes for better code structure and maintainability.
By applying these OOP principles, you can create modular, maintainable, and scalable JavaScript code. OOP in JavaScript is implemented using prototypes and, with the introduction of ES6, classes. It helps manage complexity, promotes code reuse, and improves the overall design of your applications.

122
Q

Make this work:
duplicate([1,2,3,4,5]); // [1,2,3,4,5,1,2,3,4,5]

A

Certainly! To achieve the desired result of duplicating the elements in an array, you can create a function like this:

javascript
Copy code
function duplicate(arr) {
return arr.concat(arr);
}

console.log(duplicate([1, 2, 3, 4, 5])); // Output: [1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
In this example, the concat method is used to concatenate the original array (arr) with itself, effectively duplicating its elements. The result is an array with the elements repeated.

123
Q

Create a for loop that iterates up to 100 while outputting “fizz” at multiples of 3, “buzz” at multiples of 5 and “fizzbuzz” at multiples of 3 and 5

A

You can create a for loop that iterates up to 100 and outputs “fizz,” “buzz,” or “fizzbuzz” based on the conditions. Here’s an example in JavaScript:

javascript
Copy code
for (let i = 1; i <= 100; i++) {
// Check for multiples of 3 and 5
if (i % 3 === 0 && i % 5 === 0) {
console.log(“fizzbuzz”);
} else if (i % 3 === 0) {
console.log(“fizz”);
} else if (i % 5 === 0) {
console.log(“buzz”);
} else {
console.log(i);
}
}
This loop iterates from 1 to 100 and prints “fizz” for multiples of 3, “buzz” for multiples of 5, “fizzbuzz” for multiples of both 3 and 5, and the current number for all other cases.

124
Q

What will be returned by each of these?
console.log(“hello” || “world”)
console.log(“foo” && “bar”)

A

The logical OR (||) and logical AND (&&) operators in JavaScript have interesting behaviors.

console.log(“hello” || “world”):

The logical OR operator (||) returns the first truthy operand. If the first operand is truthy, it short-circuits and returns that value. In this case, “hello” is truthy, so the result will be “hello”.
console.log(“foo” && “bar”):

The logical AND operator (&&) returns the first falsy operand or the last truthy operand. If the first operand is falsy, it short-circuits and returns that value. If all operands are truthy, it returns the last truthy operand. In this case, both “foo” and “bar” are truthy, so it returns the last truthy operand, which is “bar”.
So, the output will be:

Copy code
hello
bar

125
Q

Write an immediately invoked function expression (IIFE)

A

An immediately invoked function expression (IIFE) is a function expression that is defined and executed immediately after its creation. Here’s an example:

(function() {
console.log(“This is an IIFE!”);
})();
In this example, the function is enclosed in parentheses to make it a function expression, and then it’s immediately invoked with the trailing () at the end. This helps create a private scope for variables inside the function, preventing them from polluting the global scope.

126
Q

Traditionally, why has it been better to serve site assets from multiple domains?

A

Serving site assets from multiple domains, known as domain sharding, has traditionally been employed to overcome browser limitations on the number of concurrent connections to a single domain. This practice aimed to improve page load times by distributing asset requests across multiple domains, allowing browsers to fetch resources in parallel. However, with modern browsers relaxing these connection limits, the necessity of domain sharding has diminished, and there’s a trend toward consolidating assets on a single domain for more streamlined performance.

127
Q

Do your best to describe the process from the time you type in a website’s URL to it finishing loading on your screen.

A

When I type a website’s URL and hit enter, my browser initiates a series of steps to load the page. First, it performs a DNS (Domain Name System) lookup to translate the human-readable domain into an IP address. Once the IP is obtained, a TCP (Transmission Control Protocol) connection is established to the server. The browser then sends an HTTP request to the server, which responds with the necessary files (HTML, CSS, JavaScript, images, etc.). As these files are received, the browser starts rendering the page, creating the Document Object Model (DOM) and rendering the visual content. If there are linked resources, such as stylesheets or scripts, additional requests are made. Finally, the page is fully loaded, and I can interact with it. The entire process involves network requests, server communication, parsing, and rendering, resulting in the webpage being displayed on my screen.

128
Q

What are the differences between Long-Polling, Websockets and Server-Sent Events?

A

Long-Polling involves the client sending a request, and the server holding it until new data is available. Websockets establish a persistent, bidirectional communication channel for real-time updates. Server-Sent Events enable the server to push updates to the client over a single HTTP connection. Each has its use cases; Long-Polling for basic scenarios, Websockets for low-latency bidirectional communication, and SSE when the server needs to push updates to the client without continuous requests.

129
Q

Explain the following request and response headers:
Diff. between Expires, Date, Age and If-Modified-…
Do Not Track
Cache-Control
Transfer-Encoding
ETag
X-Frame-Options

A

Let’s break down those HTTP headers:

Expires, Date, Age:

Expires: Indicates the date and time after which the resource is considered stale.
Date: Represents the date and time when the response was generated.
Age: Specifies the time elapsed since the response was generated by an origin server.
If-Modified-Since:

Used in a conditional GET request to only retrieve the resource if it has been modified since the specified date.
Do Not Track:

A header indicating the user’s preference regarding tracking and profiling.
Cache-Control:

Directs caching mechanisms on how to handle the caching of a response.
Transfer-Encoding:

Specifies the form of encoding used to safely transfer the entity to the user.
ETag:

A unique identifier for a specific version of a resource, helping in cache validation.
X-Frame-Options:

Provides protection against clickjacking attacks by controlling whether a browser should be allowed to render a page in a frame, iframe, embed, or object.

130
Q

What are HTTP methods? List all HTTP methods that you know, and explain them.

A

HTTP methods define the actions performed on web resources. GET retrieves data, POST submits data, PUT updates or creates a resource, DELETE removes a resource, PATCH applies partial modifications, OPTIONS describes communication options, HEAD retrieves headers only, TRACE echoes the request, and CONNECT establishes a tunnel. Each method plays a specific role, facilitating communication between clients and servers while adhering to RESTful principles in web development.

131
Q

What is domain pre-fetching and how does it help with performance?

A

Domain prefetching, or DNS prefetching, is a browser feature that proactively resolves domain names before they are explicitly requested. This is done in the background, anticipating future resource needs. By resolving domain names early, the browser reduces latency when the resources are eventually requested, enhancing page loading speed. This is particularly beneficial for performance, especially in scenarios where multiple resources from different domains are used. However, it’s essential to use domain prefetching judiciously, as unnecessary prefetching can lead to increased DNS queries and potential privacy concerns.

132
Q

What is a CDN and what is the benefit of using one?

A

A Content Delivery Network (CDN) is a network of distributed servers strategically placed across various geographical locations to deliver web content, including images, stylesheets, scripts, and videos, to users more efficiently. The primary benefit of using a CDN is improved website performance and user experience. When a user requests content, the CDN serves it from the nearest server, reducing latency and speeding up load times. Additionally, CDNs help mitigate traffic spikes, distribute server load, and provide enhanced security through features like DDoS protection. Overall, CDNs contribute significantly to faster, more reliable, and scalable content delivery for websites and web applications.

133
Q

what is a RESTful API

A

A RESTful API (Representational State Transfer) is an architectural style for designing networked applications. It adheres to a set of constraints and principles, providing a standardized way for systems to communicate over HTTP. Key characteristics of a RESTful API include statelessness (each request from a client to a server must contain all the information needed to understand and fulfill the request), a uniform interface (using standard HTTP methods like GET, POST, PUT, DELETE), resource-based architecture (resources are identified by URIs), and the representation of resources in a format such as JSON or XML. RESTful APIs are widely used for building scalable and interoperable web services, making them a fundamental part of modern web development.

134
Q

What tools would you use to find a performance bug in your code?

A

To identify and address performance issues in my code, I would use a combination of tools and techniques. Firstly, browser developer tools, such as Chrome DevTools or Firefox Developer Tools, are invaluable for profiling and analyzing code execution, network requests, and memory usage. Performance monitoring services like Lighthouse or PageSpeed Insights can provide actionable insights and suggestions for improvement. Additionally, I might use specialized tools like WebPageTest to simulate different network conditions and assess the impact on performance. Profiling tools in integrated development environments (IDEs) like Visual Studio Code could help identify bottlenecks. Finally, incorporating performance testing tools like JMeter or Gatling into my continuous integration pipeline would enable automated testing for scalability and responsiveness.

135
Q

What are some ways you may improve your website’s scrolling performance?

A

To improve my website’s scrolling performance, I’ve implemented lazy loading for images and applied virtualization for large lists or tables to render only visible items, reducing initial load time. I’ve utilized hardware acceleration by leveraging CSS properties like transform and opacity for smoother animations. Implementing debouncing and throttling techniques helps limit the frequency of resource-intensive scroll-related functions. Additionally, I’ve optimized animations, minimized the use of heavy animations, and applied the will-change CSS property for elements likely to be animated. These strategies, along with utilizing scrolling libraries and performance profiling with browser developer tools, collectively contribute to a more responsive and smoother scrolling experience for users.

136
Q

Explain the difference between layout, painting and compositing.

A

In web rendering, layout is about arranging elements on the page, painting involves filling in the pixels with colors and styles, and compositing is the final step of combining painted elements into the visible output. Optimizing performance includes minimizing layout changes, reducing paint complexity, and leveraging hardware acceleration for smoother compositing, ensuring an efficient rendering process and a better user experience.

137
Q

What are some advantages/disadvantages to testing your code?

A

Testing code comes with various advantages and disadvantages. On the positive side, testing enhances code reliability by catching bugs early in the development process, ensuring more robust software. It facilitates code maintenance, making it easier to identify and fix issues during updates. Additionally, testing provides documentation for expected behavior, aiding collaboration among developers. However, testing can be time-consuming, potentially slowing down the development process. There’s also the risk of incomplete test coverage, where certain scenarios might be overlooked. Balancing the trade-offs and adopting a comprehensive testing strategy helps strike the right chord between code quality and development efficiency.

138
Q

What tools would you use to test your code’s functionality?

A

For testing code functionality, I commonly use a combination of tools and frameworks. Unit testing is essential, and I often rely on Jest for JavaScript code. Jest provides a simple and effective way to write and run unit tests. For end-to-end testing and ensuring that the entire application works as expected, I use tools like Cypress or Selenium. These tools allow for automated testing of user interactions and workflows. Additionally, I leverage linting tools like ESLint to enforce coding standards and catch potential issues early in the development process. These tools collectively contribute to a robust testing strategy, ensuring the reliability and functionality of the codebase.

139
Q

What is the difference between a unit test and a functional/integration test?

A

Unit tests are designed to check the smallest, isolated units of code, like functions or methods, ensuring they work individually. On the other hand, functional or integration tests verify the collaboration of different components or modules, ensuring they work together as a cohesive system. While unit tests focus on specific functionalities within a unit, functional/integration tests validate the interactions and integrations across multiple units to guarantee the overall system functionality. Each type of testing serves a distinct purpose in ensuring code reliability and system performance.

140
Q

What is the purpose of a code style linting tool?

A

A code style linting tool, such as ESLint, serves the purpose of enforcing consistent coding styles and identifying potential issues in a codebase. It automates the process of checking code against a predefined set of style guidelines, catching common errors, stylistic inconsistencies, and potential bugs. By adhering to a consistent coding style, developers can enhance code readability, maintainability, and collaboration. Linting tools contribute to a cleaner and more standardized codebase, facilitating better teamwork and reducing the likelihood of introducing errors or unconventional coding practices.

141
Q

What are some of the testing best practices?

A

Testing best practices are crucial for maintaining code quality and reliability. Early testing allows for the detection of issues at the beginning of the development process, reducing the cost of fixing later. Automation of tests ensures efficiency and consistency, while comprehensive test coverage guarantees that critical paths are thoroughly validated. Utilizing testing frameworks, integrating testing into the CI/CD pipeline, and practicing regular test maintenance contribute to a well-structured and reliable testing strategy. Mocking external dependencies and clear test naming enhance test isolation and readability. Additionally, including performance testing ensures the application meets speed and scalability requirements, creating a robust testing framework for sustainable development.

142
Q

Question: What is the value of foo?

var foo = 10 + ‘20’;

A

the value of foo would be the string ‘1020’. The addition operation is performed as a concatenation because one of the operands is a string. JavaScript automatically converts the numerical value 10 to a string and concatenates it with the string ‘20’, resulting in the concatenated string ‘1020’.

143
Q

What will be the output of the code below?

console.log(0.1 + 0.2 == 0.3);

A

The output of the code would be false. In JavaScript, floating-point arithmetic can lead to precision issues due to the way numbers are represented in binary. In this case, the sum of 0.1 and 0.2 does not precisely equal 0.3, resulting in a false comparison. It’s a common consideration in JavaScript to use methods like toFixed() or work with integers when precision is crucial.

144
Q

Question: How would you make this work?

add(2, 5); // 7
add(2)(5); // 7

A

To achieve this functionality, you can define the add function in two ways:

javascript
Copy code
// Approach 1: Using a function with two parameters
function add(a, b) {
return a + b;
}

// Approach 2: Using a function that returns another function
function add(a) {
return function(b) {
return a + b;
};
}

// Examples
console.log(add(2, 5)); // Output: 7
console.log(add(2)(5)); // Output: 7
In the first approach, add takes two parameters directly, while in the second approach, it takes one parameter and returns a function that takes the second parameter. Both approaches will produce the desired results.`

145
Q

What value is returned from the following statement?

“i’m a lasagna hog”.split(“”).reverse().join(“”);

A

The value returned from the given statement is the reversed string:

“goh angasal a m’i”

Explanation:

The split(“”) method splits the string into an array of characters: [“i”, “’”, “m”, “ “, “a”, “ “, “l”, “a”, “s”, “a”, “g”, “n”, “a”, “ “, “h”, “o”, “g”].
The reverse() method reverses the order of the elements in the array.
The join(“”) method joins the elements of the array into a string, resulting in the reversed string.

146
Q

What is the value of window.foo?

( window.foo || ( window.foo = “bar” ) );

A

The value of window.foo depends on whether window.foo is already defined. If window.foo is already defined and has a truthy value, then its current value will be the result. If window.foo is falsy or undefined, the expression (window.foo = “bar”) will set window.foo to the string “bar,” and the result will be “bar.”

This code snippet is a common pattern for initializing a variable if it doesn’t exist. It checks if window.foo is truthy, and if not, it assigns the value “bar” to it.

147
Q

What is the outcome of the two alerts below?

var foo = “Hello”;
(function() {
var bar = “ World”;
alert(foo + bar);
})();
alert(foo + bar);

A

The outcome of the two alerts would be:

The first alert within the immediately-invoked function expression (IIFE) will display “Hello World” because it can access both the foo variable outside its scope and the bar variable declared within the function.

The second alert outside the IIFE will result in an error. This is because the bar variable is declared within the function’s scope and is not accessible outside of it. The code will throw a ReferenceError, stating that bar is not defined.

To fix this issue, you would need to declare the bar variable outside the function if you want to access it globally.

148
Q

What is the value of foo.length?

var foo = [];
foo.push(1);
foo.push(2);

A

The value of foo.length is 2. The push method is used to add elements to the end of the array foo, and it increments the length property accordingly. In this case, two elements have been pushed into the array, resulting in a length of 2.

149
Q

What is the value of foo.x?

var foo = {n: 1};
var bar = foo;
foo.x = foo = {n: 2};

A

The value of foo.x is undefined.

Here’s the breakdown of the code:

var foo = {n: 1};: Creates an object foo with a property n set to 1.
var bar = foo;: Assigns the reference of foo to bar.
foo.x = foo = {n: 2};: Assigns a new object {n: 2} to foo and then adds a property x to the original object referenced by foo (before the reassignment). The foo.x assignment is executed before the reassignment of foo.
After this, foo refers to the new object {n: 2}, and foo.x is not defined on this new object. Therefore, foo.x is undefined.

150
Q

What does the following code print?

console.log(‘one’);
setTimeout(function() {
console.log(‘two’);
}, 0);
Promise.resolve().then(function() {
console.log(‘three’);
})
console.log(‘four’);

A

The code prints:

one
four
three
two

Here’s the explanation:

‘one’: Printed immediately.
‘four’: Printed immediately after ‘one’.
‘three’: Printed after the promise is resolved (microtask), before the setTimeout callback.
‘two’: Printed after the setTimeout callback, even though the delay is set to 0. The setTimeout callback is pushed to the message queue and executed after the current call stack is empty.

151
Q

What is the difference between these four promises?

doSomething().then(function () {
return doSomethingElse();
});

doSomething().then(function () {
doSomethingElse();
});

doSomething().then(doSomethingElse());

doSomething().then(doSomethingElse);

A

Let’s break down the differences:

doSomething().then(function () { return doSomethingElse(); });: This returns a promise that is resolved with the result of doSomethingElse().

doSomething().then(function () { doSomethingElse(); });: This returns a promise immediately after doSomething() is resolved, without waiting for the completion of doSomethingElse(). It doesn’t chain the promises.

doSomething().then(doSomethingElse());: This immediately executes doSomethingElse() when doSomething() is resolved and passes its result to then. It doesn’t wait for the promise returned by doSomething().

doSomething().then(doSomethingElse);: This is similar to the first example, but it directly passes the function reference to then, making it more concise. It returns a promise that is resolved with the result of doSomethingElse().

In summary, the key difference lies in whether you are returning a function or the result of a function in the then callback.

152
Q

What will the code below output to the console and why?

(function(){
var a = b = 3;
})();

console.log(“a defined? “ + (typeof a !== ‘undefined’));
console.log(“b defined? “ + (typeof b !== ‘undefined’));

A

The code will output:

a defined? false
b defined? true
Here’s the explanation:

Inside the immediately-invoked function expression (IIFE), var a = b = 3; is used. This line is equivalent to var a = (b = 3);. It declares a local variable a and assigns the value 3 to it, but it also assigns the value 3 to the global variable b because b is not declared with var, making it implicitly global.

Outside the IIFE, when you check the typeof a, it returns undefined because a is locally scoped within the IIFE. However, b is globally scoped, so typeof b returns ‘number’ (or ‘undefined’ if it hasn’t been assigned elsewhere).

153
Q

Consider the two functions below. Will they both return the same thing? Why or why not?

function foo1()
{
return {
bar: “hello”
};
}

function foo2()
{
return
{
bar: “hello”
};
}

A

No, they will not return the same thing. The reason is related to automatic semicolon insertion (ASI) in JavaScript.

In foo1, the object is correctly returned, and the code is equivalent to:

function foo1() {
return {
bar: “hello”
};
}

In foo2, due to ASI, the return statement is followed by a newline, which leads to the interpreter inserting a semicolon after return, effectively making it look like:

function foo2() {
return; // This line gets terminated here due to automatic semicolon insertion
{
bar: “hello”
};
}

So, foo2 will actually return undefined because the return statement is not returning the object literal. To fix this, you should keep the object literal on the same line as return:

function foo2() {
return {
bar: “hello”
};
}

154
Q

What is a cool project that you’ve recently worked on?

A

Recently, I had the opportunity to work on a project involving the redesign of a casino lobby. The design team introduced a fresh look, and my role was to implement this new design while also incorporating some additional features. The entire lobby was developed using Vue.js, allowing for a more modular and maintainable structure. It was a great experience collaborating with the design team and implementing their vision to enhance both the aesthetics and functionality of the casino lobby.

155
Q

What are some things you like about the developer tools you use?

A

I really enjoy working with the developer tools in my day-to-day tasks. Using Visual Studio Code as my primary code editor provides an excellent development experience, and I particularly appreciate the seamless integration with Git for version control. The Vue extension for debugging Vue.js applications enhances my ability to inspect and troubleshoot Vue-specific code directly in the browser using Chrome DevTools. Having a comprehensive set of tools at my disposal, from inspecting elements to profiling performance, significantly streamlines the development process and helps me deliver high-quality Vue.js applications efficiently

156
Q

Who inspires you in the front-end community?

A

I find inspiration from my senior colleagues who have a strong background in full-stack development. Their ability to seamlessly navigate both frontend and backend technologies is truly impressive. They not only demonstrate technical expertise but also showcase effective collaboration and problem-solving skills. Witnessing their successful integration of various technologies to create robust and efficient solutions motivates me to continually expand my own skill set and contribute to impactful projects in the front-end community.

157
Q

Do you have any pet projects? What kind?

A

I don’t currently have any pet projects in coding. I find fulfillment in my job projects, particularly the recent casino lobby redesign using Vue.js. Outside of coding, I engage in various hobbies like writing, crocheting, hiking, and cosplay/costuming. These activities provide a well-rounded balance to my life and allow me to explore different creative outlets beyond the coding realm.