Web Development JavaScript 5

Question 1

What does the `async` keyword do when placed before a function declaration?

Accepted Answer

Both B and C

Answer

An `async` function always returns a Promise and enables the use of `await` inside it to pause execution until a Promise settles.

Question 2

What is the correct way to clone an object shallowly in modern JavaScript?

Accepted Answer

Object.assign({}, obj)

Answer

`Object.assign({}, obj)` copies all enumerable own properties from `obj` into a new object, creating a shallow clone.

Question 3

What is 'hoisting' in JavaScript?

Accepted Answer

The behavior where variable and function declarations are moved to the top of their scope before execution

Answer

JavaScript hoisting moves declarations (not initializations) to the top of their scope during compilation, so functions and `var` declarations are available before their line in code.

Question 4

What does `Symbol()` create in JavaScript?

Accepted Answer

A unique and immutable primitive value used as object property keys

Answer

`Symbol()` creates a unique primitive that is guaranteed to be distinct from all other values, even other Symbols created with the same description.

Question 5

Which of the following correctly uses optional chaining (`?.`)?

Accepted Answer

user?.name ?? 'Guest'

Answer

`user?.name` safely accesses `name` on `user`, returning `undefined` instead of throwing if `user` is `null` or `undefined`.

Web Development Practice Test

Web Development Practice Test

Web Development JavaScript 5