135 interview questions on Javascript for developers (2024)

Medium

68 votes2888 runs4 comments

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

Web developer

Vincent Cotroat Jan 18, 2024

Medium

30 votes2655 runs3 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

21 votes2805 runs1 comment

Fix the following Javascript loop:

Web developer

loops

conditions

Camilleat Apr 27, 2023

Easy

10 votes3315 runs

3 comments

The certificate variable is not attainable outside the if loop

Web developer

variables

scope

Kahinaat Apr 6, 2022

Easy

9 votes3151 runs2 comments

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

Web developer

array

spread operator

Kahinaat Jul 19, 2024

Hard

8 votes2114 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

Hard

8 votes2074 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

Hard

7 votes2116 runs0 comment

Invert a string in Javascript

Front-end developer

arrays

strings

Jean-marie Cléryat Jan 4, 2022

Easy

6 votes3342 runs0 comment

What can be said about ECMAScript?

Web developer

standards

javascript

Kahinaat Apr 12, 2022

Medium

6 votes3292 runs0 comment

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

6 votes3139 runs2 comments

Print the number of countries in the array travel.

Web developer

array

for loop

Vincent Cotroat Sep 5, 2022

Easy

6 votes3126 runs2 comments

Write a for in loop in Javascript

Web developer

arrays

loops

Kahinaat Apr 6, 2022

Hard

6 votes2176 runs0 comment

What will this code display?

Front-end developer

javascript

function

identity

Jean-marie Cléryat Jan 4, 2022

Easy

6 votes2116 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

5 votes3104 runs0 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

5 votes2015 runs1 comment

Explain the difference between let and const in Javascript

Web developer

variables

mutability

Kahinaat Mar 21, 2022

Hard

5 votes1865 runs1 comment

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

Hard

5 votes1334 runs0 comment

What happens if we execute this code?

Web developer

Florentat Feb 29, 2024

Medium

5 votes1257 runs3 comments

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

Web developer

objects

arrays

Kahinaat Mar 21, 2022

Hard

5 votes232 runs1 comment

How to overwrite a property in an object in Javascript

Front-end developer

objects

duplicates

Vincent Cotroat Sep 19, 2022

135 interview questions on Javascriptfor developers (2024)

Test your technical skills before an interview of Javascript with 135 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

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

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

Invert a string in Javascript

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.

Print the number of countries in the array travel.

Write a for in loop in Javascript

What will this code display?

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

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

Explain the difference between let and const in Javascript

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?

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

How to overwrite a property in an object in Javascript

135 interview questions on Javascriptfor developers (2024)

Test your technical skills before an interview of Javascript with 135 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

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

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

Invert a string in Javascript

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.

Print the number of countries in the array travel.

Write a for in loop in Javascript

What will this code display?

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

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

Explain the difference between let and const in Javascript

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?

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

How to overwrite a property in an object in Javascript

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