Node.js Fundamentals

Question 1

What is the Node.js architecture?

Answer 1

Node.js uses a single-threaded event loop architecture with non-blocking I/O operations to handle concurrent client requests.

Question 2

What is the event loop in Node.js?

Answer 2

The event loop in Node.js is the mechanism that handles asynchronous operations by executing non-blocking I/O operations on a single thread.

Question 3

Advantages of Node.js event loop architecture?

Answer 3

Improved performance for I/O-heavy tasks, high concurrency, low memory consumption, fast handling of numerous simultaneous requests.

Question 4

Disadvantages of Node.js event loop architecture?

Answer 4

Can be inefficient for CPU-heavy tasks, may lead to blocking of the event loop if not properly managed.

Question 5

Best practices for Node.js event loop?

Answer 5

Offload CPU-intensive tasks to worker threads, use asynchronous I/O, avoid blocking the event loop.

Question 6

Use cases for Node.js event loop?

Answer 6

Real-time applications (chat, games), microservices, API backends, streaming services.

Question 7

Impact of Node.js event loop on system design?

Answer 7

It enables high throughput and scalability, but requires careful management of blocking operations to avoid bottlenecks.

Question 8

Architectural implications of Node.js event loop?

Answer 8

Allows building highly scalable systems, but requires balancing CPU-heavy tasks and offloading them to avoid event loop blockages.

Question 9

Performance implications of Node.js event loop?

Answer 9

Good for handling high volumes of I/O-bound requests, but less suited for CPU-heavy tasks which might slow down other requests.

Question 10

Fault tolerance in Node.js event loop?

Answer 10

Single-threaded architecture makes it susceptible to errors affecting the whole application. Use clustering and worker threads for fault tolerance.

Question 11

Monitoring and debugging Node.js event loop?

Answer 11

Use tools like Node.js built-in profiler, clinic.js, or node-inspect to monitor event loop performance and detect potential bottlenecks.

Question 12

Common interview question about the event loop?

Answer 12

Explain the event loop in Node.js and how it handles concurrency.

Question 13

Potential gotchas with Node.js event loop?

Answer 13

Blocking the event loop with synchronous code or unoptimized CPU-heavy tasks can degrade performance and cause unresponsiveness.

Question 14

What is CommonJS in Node.js?

Answer 14

CommonJS is the module system used in Node.js, allowing you to export and import modules using module.exports and require().

Question 15

What is ES Modules in Node.js?

Answer 15

ES Modules is the standard JavaScript module system that uses import and export syntax, introduced for modern JavaScript.

Question 16

Advantages of CommonJS?

Answer 16

Works synchronously and is widely supported in Node.js, simple to use with require() and module.exports.

Question 17

Advantages of ES Modules?

Answer 17

Supports import/export syntax, allows static analysis and tree shaking, and is the official module system for JavaScript.

Question 18

Disadvantages of CommonJS?

Answer 18

Synchronous loading, can lead to issues when working with asynchronous code or in browser environments.

Question 19

Disadvantages of ES Modules?

Answer 19

Not supported natively in all Node.js versions until recently, has potential compatibility issues with CommonJS modules.

Question 20

Best practices for using modules in Node.js?

Answer 20

Use ES Modules for new projects where possible, use CommonJS for compatibility, prefer named exports over default exports.

Question 21

Use cases for CommonJS?

Answer 21

Widely used in Node.js for server-side applications, packages, and libraries.

Question 22

Use cases for ES Modules?

Answer 22

Client-side JavaScript, modern Node.js apps, projects using tree shaking and bundling tools.

Question 23

Architectural implications of using CommonJS?

Answer 23

CommonJS allows dynamic module loading, but can cause issues with synchronous imports in larger applications.

Question 24

Performance implications of using ES Modules?

Answer 24

ES Modules enable better optimization, like tree shaking, for bundling and reduce the overall app size.

Question 25

Fault tolerance with modules?

Answer 25

In Node.js, fault tolerance can be enhanced by structuring code into well-defined modules, catching errors in module boundaries.

Question 26

Monitoring and debugging modules?

Answer 26

Use `console.log()` to check module imports and exports, tools like `node --inspect` help debug the module system.

Question 27

Common interview question about modules?

Answer 27

What is the difference between CommonJS and ES Modules in Node.js?

Question 28

Potential gotchas with modules?

Answer 28

Mixing CommonJS and ES Modules can lead to compatibility issues, be mindful of async vs sync loading behaviors.

Question 29

What is a Node.js process?

Answer 29

A Node.js process is an instance of the Node runtime, it is the environment where JavaScript code is executed.

Question 30

What is the Buffer class in Node.js?

Answer 30

Buffer is a built-in object in Node.js used to handle raw binary data directly in memory, without needing to deal with string encoding.

Question 31

Advantages of using Buffer?

Answer 31

Efficient for working with binary data, avoids encoding overhead when reading or writing files or data streams.

Question 32

Disadvantages of using Buffer?

Answer 32

Can lead to memory issues if large buffers are not managed correctly, difficult to handle for large data processing.

Question 33

Best practices for using Buffer?

Answer 33

Always allocate the right size for buffers, release memory when no longer needed, use `Buffer.alloc()` instead of `new Buffer()` to avoid security risks.

Question 34

Use cases for Buffer?

Answer 34

Handling binary data, working with streams, interacting with binary file formats, communication with hardware.

Question 35

Architectural implications of Process and Buffer?

Answer 35

Proper memory management is crucial, improper handling of buffers can lead to memory leaks or crashes in long-running processes.

Question 36

Performance implications of Buffer?

Answer 36

Buffers are efficient for dealing with raw data, but allocating large buffers without managing memory can lead to performance degradation.

Question 37

Fault tolerance in Buffer?

Answer 37

Handle buffer allocation errors gracefully, ensure that buffer sizes do not exceed memory limits, avoid over-allocating memory.

Question 38

Monitoring and debugging Process & Buffer?

Answer 38

Use Node.js built-in process monitoring tools like `process.memoryUsage()`, check buffer sizes and allocations during debugging.

Question 39

Common interview question about Process and Buffer?

Answer 39

How does Node.js handle memory management and what are the differences between Buffers and strings?

Question 40

Potential gotchas with Process and Buffer?

Answer 40

Not freeing up buffers or managing large memory allocations can cause memory leaks or crashes.

Question 41

What is the File System module in Node.js?

Answer 41

The File System (fs) module allows interaction with the file system, enabling reading, writing, and managing files.

Question 42

What are Streams in Node.js?

Answer 42

Streams in Node.js are abstract interfaces for handling streaming data, which can be read or written in chunks.

Question 43

Advantages of using File System module?

Answer 43

Enables efficient file handling, supports both synchronous and asynchronous operations, and works with large files.

Question 44

Disadvantages of using File System module?

Answer 44

Synchronous file operations can block the event loop, leading to performance degradation in high-concurrency applications.

Question 45

Advantages of using Streams?

Answer 45

Efficient memory usage, allows for processing of large files or data in chunks without loading everything into memory.

Question 46

Disadvantages of using Streams?

Answer 46

Complexity in managing stream flows, may require handling backpressure when writing large volumes of data.

Question 47

Best practices for using Streams?

Answer 47

Use streams for large data handling, implement proper error handling, manage backpressure to avoid memory overflow.

Question 48

Use cases for File System?

Answer 48

Reading and writing large files, managing configurations, logging, and database storage.

Question 49

Use cases for Streams?

Answer 49

Video/audio streaming, reading large files, piping data between processes or services.

Question 50

Architectural implications of File System and Streams?

Answer 50

Streams help reduce memory usage, but they require careful error and backpressure management.

Question 51

Performance implications of Streams?

Answer 51

Streams improve performance when dealing with large datasets, as they avoid loading everything into memory.

Question 52

Fault tolerance with Streams?

Answer 52

Handle errors in streams (e.g., file not found) and backpressure to prevent crashes or memory issues.

Question 53

Monitoring and debugging File System and Streams?

Answer 53

Monitor the status of streams with events like `data`, `end`, and `error`, use logging to monitor file read/write operations.

Question 54

Common interview question about Streams?

Answer 54

What is the difference between streams and buffers in Node.js?

Question 55

Potential gotchas with File System and Streams?

Answer 55

Improper error handling or not managing backpressure properly can result in data loss or crashes.

Question 56

What is error handling in Node.js?

Answer 56

Error handling in Node.js involves using try/catch blocks for synchronous code and handling asynchronous errors with callbacks or promises.

Question 57

What are the common strategies for error handling in Node.js?

Answer 57

Use `try/catch` for synchronous errors, `callback` with error-first argument for asynchronous errors, and `Promise.catch()` for promise rejections.

Question 58

Advantages of proper error handling?

Answer 58

Improved reliability, prevents unhandled errors from crashing the application, better debugging and logging.

Question 59

Disadvantages of improper error handling?

Answer 59

Can lead to unhandled exceptions, crashes, security vulnerabilities, or data loss.

Question 60

Best practices for error handling in Node.js?

Answer 60

Always handle asynchronous errors, log meaningful error messages, provide custom error classes for better debugging.

Question 61

Use cases for error handling?

Answer 61

Handling failed API requests, file reading errors, and database connection failures.

Question 62

Impact of error handling on system design?

Answer 62

Error handling ensures graceful degradation and robustness, leading to fault-tolerant systems.

Question 63

Architectural implications of error handling?

Answer 63

Centralized error handling, use of logging systems for tracking errors, defining custom error types.

Question 64

Performance implications of error handling?

Answer 64

Improper handling can lead to unnecessary retries or performance bottlenecks, excessive logging might degrade performance.

Question 65

Fault tolerance in error handling?

Answer 65

Gracefully handle errors by retrying or falling back to alternate systems, provide fallbacks to maintain service.

Question 66

Monitoring and debugging error handling?

Answer 66

Use logging frameworks like `winston` or `bunyan` to capture and monitor errors, integrate with monitoring systems.

Question 67

Common interview question about error handling?

Answer 67

How would you handle errors in a Node.js application?

Question 68

Potential gotchas with error handling?

Answer 68

Not handling asynchronous errors properly can lead to uncaught exceptions, causing application crashes.