MEAN Node.js Async Patterns and Performance 2

Question 1

What is the purpose of Node.js streams in a MEAN stack application?

Accepted Answer

Process data in chunks for memory efficiency, ideal for large file uploads or database exports

Answer

Streams process data incrementally in chunks rather than loading it all into memory, making them essential for handling large files, CSV exports, or proxying requests.

Question 2

What does `async/await` syntax do in Node.js?

Accepted Answer

Makes asynchronous Promise-based code look synchronous, improving readability and error handling

Answer

async/await is syntactic sugar over Promises that lets you write asynchronous code in a linear, readable style, with try/catch for error handling instead of .catch().

Question 3

What is the Node.js `EventEmitter` class used for?

Accepted Answer

Implements the observer pattern allowing objects to emit named events that listeners can respond to

Answer

EventEmitter lets you create custom event-driven architectures; objects emit named events and registered listeners are called asynchronously.

Question 4

What is `util.promisify()` used for in Node.js?

Accepted Answer

Converts callback-style functions following the error-first pattern into Promise-returning functions

Answer

util.promisify() wraps legacy Node.js callback-based functions (like fs.readFile) into functions that return Promises, enabling async/await usage.

Question 5

What is backpressure in Node.js streams and why does it matter?

Accepted Answer

When a writable stream can't consume data as fast as the readable produces it, and the readable should pause

Answer

Backpressure occurs when a consumer can't keep up with a producer; proper handling via the 'drain' event prevents unbounded memory growth in streaming pipelines.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Node.js Async Patterns and Performance 2