79 interview questions on Javascript for developers (2024)

Hard

8 votes2005 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

6 votes1974 runs

3 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

5 votes2067 runs0 comment

What will this code display?

Front-end developer

javascript

function

identity

Jean-marie Cléryat Jan 4, 2022

Easy

5 votes2009 runs

1 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

5 votes2001 runs

1 comment

Invert a string in Javascript

Front-end developer

arrays

strings

Jean-marie Cléryat Jan 4, 2022

Hard

5 votes222 runs1 comment

How to overwrite a property in an object in Javascript

Front-end developer

objects

duplicates

Vincent Cotroat Sep 19, 2022

Hard

4 votes2033 runs

2 comments

What is the value of `obj.hello` after executing these few lines of code?

Front-end developer

objects

arrays

strings

Jean-marie Cléryat Oct 20, 2023

Hard

3 votes2039 runs

1 comment

Explain the difference between `proto` and `prototype` in Javascript

Front-end developer

prototype

constructor

Jean-marie Cléryat Jan 4, 2022

Hard

3 votes2039 runs0 comment

Identify the reasons why this code will not work correctly:

Front-end developer

javascript

html

form

Jean-marie Cléryat Jan 4, 2022

Medium

3 votes2032 runs

1 comment

How to make an AJAX call to an external domain that makes public data available.

Front-end developer

ajax

authentication

Jean-marie Cléryat Jan 4, 2022

Hard

3 votes2016 runs

2 comments

How to call a function inside a function in Javascript

Front-end developer

functions

objects

Jean-marie Cléryat Jan 4, 2022

Hard

3 votes1994 runs0 comment

Explain the 2 phases of event propagation in the DOM.

Front-end developer

event

event propagation

Jean-marie Cléryat Jan 4, 2022

Medium

3 votes1992 runs0 comment

Write a Javascript code that will display the letters A, B, C, D in the console.

Front-end developer

array

function

Jean-marie Cléryat Jan 4, 2022

Medium

3 votes263 runs1 comment

Print the value of the variable name and age in the function sayHi()

Front-end developer

functions

variables

Vincent Cotroat Sep 19, 2022

Medium

3 votes219 runs0 comment

Compare two numbers in Javascript

Front-end developer

equality

comparison

type

Vincent Cotroat Sep 19, 2022

Hard

2 votes2060 runs0 comment

Which of the following features are part of version ES2015(formerly ES6)?

Front-end developer

es6

promises

arrow functions

Jean-marie Cléryat Jan 4, 2022

Easy

2 votes2053 runs

3 comments

Write a Javascript code that displays the contents of the table : Peter, Paul, Jacques, and the length of the table.

Front-end developer

arrays

console.log

push

Jean-marie Cléryat Jan 4, 2022

Hard

2 votes2027 runs1 comment

Which statements are true about JavaScript Strict Mode?

Front-end developer

javascript

strict mode

Jean-marie Cléryat Jan 4, 2022

Hard

2 votes1990 runs

1 comment

What will be the first thing that the following code displays?

Front-end developer

inheritance

prototype

constructor

Jean-marie Cléryat Jan 4, 2022

Expert

2 votes258 runs0 comment

Write a function that calculates the perimeter of a circle.

Front-end developer

functions

objects

Vincent Cotroat Sep 19, 2022

79 interview questions on Javascriptfor developers (2024)

Test your technical skills before an interview of Javascript with 79 corrected questions. Beginner, Intermediate or Expert level.

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

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

What will this code display?

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

Invert a string in Javascript

How to overwrite a property in an object in Javascript

What is the value of `obj.hello` after executing these few lines of code?

Explain the difference between `proto` and `prototype` in Javascript

Identify the reasons why this code will not work correctly:

How to make an AJAX call to an external domain that makes public data available.

How to call a function inside a function in Javascript

Explain the 2 phases of event propagation in the DOM.

Write a Javascript code that will display the letters A, B, C, D in the console.

Print the value of the variable name and age in the function sayHi()

Compare two numbers in Javascript

Which of the following features are part of version ES2015(formerly ES6)?

Write a Javascript code that displays the contents of the table : Peter, Paul, Jacques, and the length of the table.

Which statements are true about JavaScript Strict Mode?

What will be the first thing that the following code displays?

Write a function that calculates the perimeter of a circle.

79 interview questions on Javascriptfor developers (2024)

Test your technical skills before an interview of Javascript with 79 corrected questions. Beginner, Intermediate or Expert level.

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

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

What will this code display?

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

Invert a string in Javascript

How to overwrite a property in an object in Javascript

What is the value of `obj.hello` after executing these few lines of code?

Explain the difference between `__proto__` and `prototype` in Javascript

Identify the reasons why this code will not work correctly:

How to make an AJAX call to an external domain that makes public data available.

How to call a function inside a function in Javascript

Explain the 2 phases of event propagation in the DOM.

Write a Javascript code that will display the letters A, B, C, D in the console.

Print the value of the variable name and age in the function sayHi()

Compare two numbers in Javascript

Which of the following features are part of version ES2015(formerly ES6)?

Write a Javascript code that displays the contents of the table : Peter, Paul, Jacques, and the length of the table.

Which statements are true about JavaScript Strict Mode?

What will be the first thing that the following code displays?

Write a function that calculates the perimeter of a circle.

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

Explain the difference between `proto` and `prototype` in Javascript