Node.js Core Modules & Event Loop 3

Question 1

Which Node.js core module allows you to create child processes?

Accepted Answer

child_process

Answer

The `child_process` module provides `spawn`, `exec`, `execFile`, and `fork` to create and communicate with child processes.

Question 2

What is the difference between `Buffer.alloc()` and `Buffer.allocUnsafe()`?

Accepted Answer

alloc() zero-fills the memory; allocUnsafe() does not and may contain old data

Answer

`Buffer.alloc()` initializes memory to zero for security, while `Buffer.allocUnsafe()` skips initialization for speed but may expose old memory contents.

Question 3

When both `setImmediate()` and `setTimeout(fn, 0)` are called within the main module (not inside an I/O callback), which executes first?

Accepted Answer

The order is non-deterministic

Answer

Outside an I/O cycle, the execution order of `setImmediate` vs `setTimeout(fn,0)` is non-deterministic due to timing constraints of the process.

Question 4

What does `require.resolve()` return without actually loading the module?

Accepted Answer

The resolved filename/path of the module

Answer

`require.resolve()` performs the module lookup algorithm and returns the resolved absolute file path without executing or caching the module.

Question 5

Which `os` module method returns the amount of free system memory in bytes?

Accepted Answer

os.freemem()

Answer

`os.freemem()` returns the amount of free operating system memory in bytes at the time of the call.

Node.js Practice Test

Node.js Practice Test

Node.js Core Modules & Event Loop 3