138 interview questions on Javascript for developers (2025)

Medium

97 votes3794 runs5 comments

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

Web developer

Vincent Cotroat Jan 18, 2024

Medium

42 votes3478 runs4 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

24 votes3598 runs

2 comments

Fix the following Javascript loop:

Web developer

loops

conditions

Camilleat Apr 27, 2023

Easy

11 votes4062 runs

5 comments

The certificate variable is not attainable outside the if loop

Web developer

variables

scope

Kahinaat Apr 6, 2022

Easy

11 votes3874 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

11 votes3819 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

Easy

10 votes4086 runs0 comment

What can be said about ECMAScript?

Web developer

standards

javascript

Kahinaat Apr 12, 2022

Medium

10 votes4063 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

Easy

10 votes3850 runs2 comments

Write a for in loop in Javascript

Web developer

arrays

loops

Kahinaat Apr 6, 2022

Hard

10 votes2274 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

Medium

9 votes3926 runs

5 comments

Print the number of countries in the array travel.

Web developer

array

for loop

Vincent Cotroat Sep 5, 2022

Hard

8 votes2309 runs

2 comments

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

Front-end developer

javascript

equality

Jean-marie Cléryat Jan 4, 2022

Easy

7 votes3925 runs

2 comments

Filter the elements of an array in Javascript

Web developer

array

filter

Kahinaat Apr 6, 2022

Easy

7 votes2805 runs

1 comment

Find the index of the last element of an array in JavaScript

Web developer

arrays

index

Axelat Sep 4, 2023

Hard

7 votes2382 runs0 comment

What will this code display?

Front-end developer

javascript

function

identity

Jean-marie Cléryat Jan 4, 2022

Hard

7 votes2330 runs

1 comment

Invert a string in Javascript

Front-end developer

arrays

strings

Jean-marie Cléryat Jan 4, 2022

Easy

7 votes2304 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

Hard

7 votes1507 runs3 comments

Access the value of the 'level' attribute in a Javascript object

Web developer

objects

arrays

Kahinaat Mar 21, 2022

Easy

6 votes3835 runs0 comment

Add Lyon to the end of the city array

Web developer

arrays

push

Kahinaat Mar 29, 2022

Medium

6 votes2647 runs

1 comment

Get the current page URL in Javascript

Web developer

javascript

url

Damienat Sep 4, 2023

138 interview questions on Javascriptfor developers (2025)

Test your technical skills before an interview of Javascript with 138 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'

What can be said about ECMAScript?

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

Write a for in loop in Javascript

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

Print the number of countries in the array travel.

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

Filter the elements of an array in Javascript

Find the index of the last element of an array in JavaScript

What will this code display?

Invert a string in Javascript

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

Access the value of the 'level' attribute in a Javascript object

Add Lyon to the end of the city array

Get the current page URL in Javascript

138 interview questions on Javascriptfor developers (2025)

Test your technical skills before an interview of Javascript with 138 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'

What can be said about ECMAScript?

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

Write a for in loop in Javascript

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

Print the number of countries in the array travel.

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

Filter the elements of an array in Javascript

Find the index of the last element of an array in JavaScript

What will this code display?

Invert a string in Javascript

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

Access the value of the 'level' attribute in a Javascript object

Add Lyon to the end of the city array

Get the current page URL in Javascript

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