JavaScript Node.js Basics 3

Question 1

What is the Node.js event loop's primary role?

Accepted Answer

To manage the execution of asynchronous callbacks by monitoring the call stack and callback queue

Answer

The event loop continuously checks whether the call stack is empty and, if so, pushes the next callback from the queue onto the stack for execution.

Question 2

Which of the following is NOT a valid phase of the Node.js event loop?

Accepted Answer

compile

Answer

The event loop phases are timers, pending callbacks, idle/prepare, poll, check, and close callbacks — there is no 'compile' phase.

Question 3

What does `setImmediate()` do in Node.js?

Accepted Answer

Schedules a callback to run after I/O events in the current iteration of the event loop

Answer

`setImmediate()` schedules its callback in the `check` phase, which runs after I/O callbacks in the same event loop iteration.

Question 4

What is `process.nextTick()` used for in Node.js?

Accepted Answer

To schedule a callback to run before any I/O events but after the current operation completes

Answer

`process.nextTick()` queues a callback in the nextTick queue, which is drained before the event loop continues to any other phase.

Question 5

In Node.js, which module is used to create child processes?

Accepted Answer

child_process

Answer

The built-in `child_process` module provides `spawn()`, `exec()`, `execFile()`, and `fork()` to create and communicate with child processes.

JavaScript Practice Test