Node.js

Question 1

What is the process object in the Node.js program?

Answer 1

The process object is a global that provides information about, and control over, the current Node.js process. As a global, it is always available to Node.js applications without using require().

Question 2

How do you access the process object in a Node.js program?

Answer 2

Just call process.

Question 3

What is the data type of process.argv in Node.js?

Answer 3

It returns an array containing the command line arguments when the Node.js process was launched. The first element will be process.execPath. The second element will be the path to the JS file being executed. The remaining elements will be any additional command line arguments.

Question 4

What is process.execPath?

Answer 4

The process.execPath property returns the absolute pathname of the executable that started the Node.js process.

Question 5

What is a JavaScript module?

Answer 5

In the Node.js module system, each file is treated as a separate module.

Question 6

What values are passed into a Node.js module’s local scope?

Answer 6

exports (object), require (function), module (object), __filename (string), __dirname (string)

Question 7

Give two examples of truly global variables in a Node.js program.

Answer 7

console, process

Question 8

What is the JS Event Loop?

Answer 8

Its job is to continuously watch both the stack and message queue. When the stack becomes empty, it checks the message queue to see if there are any messages waiting to be processed. If there are, it puts them into the call stack one at a time and executes them. Each message is associated with a function such as a callback or an event.

Question 9

What is a directory?

Answer 9

is a special type of file that holds information about more directories and files

Question 10

What is a relative file path?

Answer 10

a file relative to the current page

Question 11

What is an absolute file path?

Answer 11

a full URL to a file

Question 12

What module does Node.js include for manipulating the file system?

Answer 12

We include the fs module

Question 13

What method is available in the Node.js fs module for writing data to a file?

Answer 13

fs.writeFile

Question 14

Are file operations using the fs module synchronous or asynchronous?

Answer 14

asynchronous

Question 15

What is JSON?

Answer 15

JSON is a text-based data format following JS object syntax, which was popularized by Douglas Crockford. JSON exists as a string.

Question 16

What are serialization and deserialization?

Answer 16

Converting a string to a native object is called deserialization, while converting a native object to a string so it can be transmitted across the network is called serialization.

Question 17

Why are serialization and deserialization useful?

Answer 17

Useful when you want to transmit data across a network

Question 18

How to you serialize data into a JSON string using JavaScript?

Answer 18

JSON.stringify()

Question 19

How do you deserialize a JSON string using JavaScript?

Answer 19

JSON.parse()

Question 20

What is NPM?

Answer 20

npm is a package manager for the JS programming language. It’s a way to reuse code from other developers and also a way to share your code with them and it makes it easy to manage the different versions of code.

Question 21

What is a package?

Answer 21

A package in Node.js contains all the files you need for a module. Modules are JS libraries you can include in your project.
Video: Reusable codes == packages(or sometimes module)

A package is a directory with one or more files in it that also has a file called package.json with some metadata about this package.

Question 22

How can you create a package.json with npm?

Answer 22

Go to the directory where you want to create the package.json file and then run npm init –yes

Question 23

What is a dependency and how do you add one to a package?

Answer 23

When you install an npm package using npm install , you are installing it as a dependency. The package is automatically listed in the package.json file, under the dependencies list.

The dependencies are the modules that the project relies on to function properly.

Question 24

What happens when you add a dependency to a package with npm?

Answer 24

The packages listed under the dependencies are required by your application in production.

Question 25

How do you add express to your package dependencies?

Answer 25

Use npm to install the express package from the npm registry.

Question 26

What Express application method starts the server and binds it to a network PORT?

Answer 26

listen

Question 27

How do you mount(attaching) a middleware with an Express application?

Answer 27

Bind application-level middleware to an instance of the app object by using the app.use() and app.method() functions, where METHOD is the http method of the request that the middleware function handles (such as GET, PUT, or POST) in lowercase.

Question 28

Which objects does an Express application pass to your middleware to manage the request/response lifecycle of the server?

Answer 28

request object, response object and next middleware function

Question 29

What does express.static() return?

Answer 29

returns a middleware function

Question 30

What is the local __dirname variable in a Node.js module?

Answer 30

The directory name of the current module

Question 31

What does the join() method of Node’s path module do?

Answer 31

The path.join() method joins all given path segments together using the platform-specific separator as a delimiter, then normalizes the resulting path.

Question 32

(express) What is the significance of an HTTP request’s method?

Answer 32

It tells the server which action was requested by the client.

Question 33

What is Webpack?

Answer 33

Webpack is a static module bundler for modern JS applications. When web pack processes your application, it internally builds a dependency graph which maps every module your project needs and generates one or more bundles.

Question 34

How do you add a devDependency to a package?

Answer 34

npm install –save-dev

Question 35

What is an NPM script?

Answer 35

NPM scripts are written as usual JSON key-value pairs where the key is the name of the script and the value contains the script you want to execute.
Also, they are simply terminal commands.