Web Development JavaScript 2

Question 1

What does the `typeof` operator return for `null`?

Accepted Answer

'object'

Answer

`typeof null` returns `'object'` due to a long-standing bug in JavaScript that was never fixed for backwards compatibility.

Question 2

Which method removes the last element from an array and returns it?

Accepted Answer

pop()

Answer

`Array.prototype.pop()` removes and returns the last element, mutating the original array.

Question 3

What is the output of `console.log(0.1 + 0.2 === 0.3)` in JavaScript?

Accepted Answer

false

Answer

Floating-point arithmetic in JavaScript produces `0.30000000000000004`, so the strict equality check returns `false`.

Question 4

What does the `Array.from()` method do?

Accepted Answer

Creates a new Array instance from an array-like or iterable object

Answer

`Array.from()` creates a new array from array-like objects (e.g., NodeLists, strings) or iterables.

Question 5

What is a closure in JavaScript?

Accepted Answer

A function that retains access to its lexical scope even after the outer function has returned

Answer

A closure is created when an inner function captures and remembers variables from its surrounding scope.

Web Development Practice Test