JavaScript Interview MCQ Questions With Answers

Let

Var

Int

Const

The variables cannot be accessed outside the function in which they are declared.

The variables can be used globally.

The variables can be used globally.

The variable is only accessible inside the block(if-else/for block) inside which it is declared

Both a and c

Var

Let

Const

Both b and c

Functions are basically a statement which returns a constant value.

Functions are basically a set of statements that perform some task

Functions are one of the data types in JavaScript.

All of these

Map

Filter

Reduce

All of these

Functions

Class

Array

Object

Through destructuring, we can unpack values from arrays or object properties into separate variables.

Destructuring allows us to restructure object properties

Destructuring allows us to restructure array elements.

All of these.

Abc 1

Throws error

Null null

Undefined undefined

It is the process of combining two or more functions to create a new function.

The function declaration is termed as function composition in JavaScript

Both a and b

None of these

#This is a comment.

##This is a comment .

/This is a comment.

//This is a comment

Func = func.bind(this)

Let func = () => {}

Both a and b

None of these

Function abc() {}

Var abc = () => {} 

Both a and b

None of these

Null

Undefined

Throws error

True

Map

Filter

Reduce

ForEach

True

False

1,3,5,7

2,4,6,8

Function sum(...theArgs) {}

Function sum(theArgs...) {}

Function sum(theArgs) {} 

Function sum([theArgs]) {}

Element.addListener(event => {})

AddListener(element, event => {}) 

AddEventListener(element, event => {})

Element.addEventListener(event => {})

Data Object Model

Document or Model

Document Object Model

Document Object Meduim

JSON.parse(string)

JSON.convertToObject(string)

JSON.object(string)

None of these

Object.keys(obj)

Object.values(obj)

Object.entries(obj)

All of these