MEAN Node.js Async Patterns and Performance

Question 1

What is the Node.js Event Loop and why is it important for MEAN stack applications?

Accepted Answer

A single-threaded mechanism that processes async callbacks without blocking, enabling high concurrency

Answer

Node.js's event loop processes I/O callbacks, timers, and promises on a single thread without blocking, making it efficient for high-concurrency API servers.

Question 2

What is the difference between `process.nextTick()` and `setImmediate()` in Node.js?

Accepted Answer

nextTick() fires before I/O callbacks in the current iteration; setImmediate() fires after I/O callbacks in the next iteration

Answer

process.nextTick() callbacks run before any I/O events in the current event loop iteration, while setImmediate() runs in the check phase of the next iteration.

Question 3

What are Node.js Worker Threads used for?

Accepted Answer

Running CPU-intensive JavaScript in parallel on separate threads without blocking the event loop

Answer

Worker Threads (worker_threads module) allow Node.js to run JavaScript in parallel threads, ideal for CPU-bound tasks that would otherwise block the event loop.

Question 4

What does `Promise.all()` do in Node.js async programming?

Accepted Answer

Runs multiple Promises in parallel and resolves when all complete or rejects when any fails

Answer

Promise.all() takes an array of Promises, starts them all simultaneously, and returns a single Promise that resolves with an array of all results when every Promise resolves.

Question 5

What is Node.js clustering and how does it relate to a MEAN stack API server?

Accepted Answer

Creates multiple worker processes that share the same server port to utilize all CPU cores

Answer

The cluster module forks multiple worker processes (one per CPU core) that all listen on the same port, allowing Node.js to handle more concurrent requests.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Node.js Async Patterns and Performance