137 interview questions on Javascript for developers (2025)

Medium

85 votes3348 runs

5 comments

Understanding the differences between `map()` and `forEach()` methods in JavaScript

Web developer

Vincent Cotroat Jan 18, 2024

Medium

37 votes3063 runs

4 comments

Write a JavaScript function that fetches data from an API and logs it to the console.

Web developer

promises

async

Vincent Cotroat Mar 28, 2023

Easy

22 votes3199 runs

2 comments

Fix the following Javascript loop:

Web developer

loops

conditions

Camilleat Apr 27, 2023

Easy

10 votes3692 runs

5 comments

The certificate variable is not attainable outside the if loop

Web developer

variables

scope

Kahinaat Apr 6, 2022

Easy

10 votes3520 runs

3 comments

Use spread operator to split an array into two arrays in Javascript

Web developer

array

spread operator

Kahinaat Jul 19, 2024

Easy

10 votes3469 runs

1 comment

Write a Javascript code that displays 'Adversity is not to be feared' and 'There is potentially a real danger'

Web developer

booleans

conditionals

Adrienat Mar 30, 2022

Hard

9 votes2161 runs3 comments

Write a Javascript code that prints the indexes of an array.

Front-end developer

array

for loop

Jean-marie Cléryat Nov 8, 2023

Easy

8 votes3722 runs0 comment

What can be said about ECMAScript?

Web developer

standards

javascript

Kahinaat Apr 12, 2022

Hard

8 votes2192 runs1 comment

Which of the following equality(s) are true? 0 == '', 'f' + 1 == 'f1'

Front-end developer

javascript

equality

Jean-marie Cléryat Jan 4, 2022

Medium

7 votes3677 runs

2 comments

Write a switch statement that checks if a person can go down a slide based on their weight and height.

Web developer

switch

if else conditions

Kahinaat Apr 6, 2022

Medium

7 votes3531 runs

4 comments

Print the number of countries in the array travel.

Web developer

array

for loop

Vincent Cotroat Sep 5, 2022

Easy

7 votes3486 runs2 comments

Write a for in loop in Javascript

Web developer

arrays

loops

Kahinaat Apr 6, 2022

Hard

7 votes2209 runs0 comment

Invert a string in Javascript

Front-end developer

arrays

strings

Jean-marie Cléryat Jan 4, 2022

Easy

7 votes2200 runs0 comment

Which of the following is the most optimized method for creating a literal object?

Front-end developer

javascript

objects

Jean-marie Cléryat Jan 4, 2022

Easy

6 votes3555 runs

2 comments

Filter the elements of an array in Javascript

Web developer

array

filter

Kahinaat Apr 6, 2022

Medium

6 votes2405 runs

1 comment

Get the current page URL in Javascript

Web developer

javascript

url

Damienat Sep 4, 2023

Hard

6 votes2262 runs0 comment

What will this code display?

Front-end developer

javascript

function

identity

Jean-marie Cléryat Jan 4, 2022

Hard

6 votes2251 runs

2 comments

Write a switch statement in Javascript that checks if a person is allowed to go down a slide.

Web developer

switch

if else conditions

Mathisat Oct 20, 2023

Expert

6 votes1733 runs0 comment

What happens if we execute this code?

Web developer

Florentat Feb 29, 2024

Hard

5 votes2203 runs1 comment

How to call a function inside a function in Javascript

Front-end developer

functions

objects

Jean-marie Cléryat Jan 4, 2022

137 interview questions on Javascriptfor developers (2025)

Test your technical skills before an interview of Javascript with 137 corrected questions. Beginner, Intermediate or Expert level.

Understanding the differences between `map()` and `forEach()` methods in JavaScript

Write a JavaScript function that fetches data from an API and logs it to the console.

Fix the following Javascript loop:

The certificate variable is not attainable outside the if loop

Use spread operator to split an array into two arrays in Javascript

Write a Javascript code that displays 'Adversity is not to be feared' and 'There is potentially a real danger'

Write a Javascript code that prints the indexes of an array.

What can be said about ECMAScript?

Which of the following equality(s) are true? 0 == '', 'f' + 1 == 'f1'

Write a switch statement that checks if a person can go down a slide based on their weight and height.

Print the number of countries in the array travel.

Write a for in loop in Javascript

Invert a string in Javascript

Which of the following is the most optimized method for creating a literal object?

Filter the elements of an array in Javascript

Get the current page URL in Javascript

What will this code display?

Write a switch statement in Javascript that checks if a person is allowed to go down a slide.

What happens if we execute this code?

How to call a function inside a function in Javascript

137 interview questions on Javascriptfor developers (2025)

Test your technical skills before an interview of Javascript with 137 corrected questions. Beginner, Intermediate or Expert level.

Understanding the differences between `map()` and `forEach()` methods in JavaScript

Write a JavaScript function that fetches data from an API and logs it to the console.

Fix the following Javascript loop:

The certificate variable is not attainable outside the if loop

Use spread operator to split an array into two arrays in Javascript

Write a Javascript code that displays 'Adversity is not to be feared' and 'There is potentially a real danger'

Write a Javascript code that prints the indexes of an array.

What can be said about ECMAScript?

Which of the following equality(s) are true? 0 == '', 'f' + 1 == 'f1'

Write a switch statement that checks if a person can go down a slide based on their weight and height.

Print the number of countries in the array travel.

Write a for in loop in Javascript

Invert a string in Javascript

Which of the following is the **most optimized** method for creating a literal object?

Filter the elements of an array in Javascript

Get the current page URL in Javascript

What will this code display?

Write a switch statement in Javascript that checks if a person is allowed to go down a slide.

What happens if we execute this code?

How to call a function inside a function in Javascript

Which of the following is the most optimized method for creating a literal object?