Node.js Core Modules & Event Loop 2

Question 1

Which phase of the Node.js event loop processes I/O callbacks that were deferred from the previous iteration?

Accepted Answer

pending callbacks

Answer

The 'pending callbacks' phase executes I/O callbacks deferred to the next loop iteration, such as TCP errors.

Question 2

What does `process.nextTick()` do relative to the event loop phases?

Accepted Answer

Runs at the end of the current event loop iteration before moving to the next phase

Answer

`process.nextTick()` callbacks execute after the current operation completes but before the event loop continues to the next phase.

Question 3

Which core module provides the `EventEmitter` class?

Accepted Answer

events

Answer

The `events` core module exports the `EventEmitter` class which is the foundation of Node.js event-driven architecture.

Question 4

What is the default maximum number of listeners for a single event on an EventEmitter before a warning is emitted?

Accepted Answer

10

Answer

Node.js emits a memory leak warning when more than 10 listeners are added for a single event; this limit is configurable via `setMaxListeners()`.

Question 5

Which method of the `fs` module reads a file without buffering the entire content in memory?

Accepted Answer

fs.createReadStream()

Answer

`fs.createReadStream()` returns a Readable stream that reads the file in chunks, avoiding loading the whole file into memory.

Node.js Practice Test