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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.

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79 questions
Hard
8 votes2093 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
7 votes2092 runs0 comment

Invert a string in Javascript

Front-end developer
arrays
strings
Jean-marie Cléryat Jan 4, 2022
Hard
7 votes2053 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
6 votes2153 runs0 comment

What will this code display?

Front-end developer
javascript
function
identity
Jean-marie Cléryat Jan 4, 2022
Easy
6 votes2099 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
5 votes228 runs1 comment

How to overwrite a property in an object in Javascript

Front-end developer
objects
duplicates
Vincent Cotroat Sep 19, 2022
Hard
4 votes2124 runs0 comment

Identify the reasons why this code will not work correctly:

Front-end developer
javascript
html
form
Jean-marie Cléryat Jan 4, 2022
Hard
4 votes2115 runs1 comment

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
4 votes2103 runs1 comment

How to call a function inside a function in Javascript

Front-end developer
functions
objects
Jean-marie Cléryat Jan 4, 2022
Hard
3 votes2158 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
3 votes2140 runs2 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
3 votes2128 runs0 comment

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

Front-end developer
prototype
constructor
Jean-marie Cléryat Jan 4, 2022
Medium
3 votes2118 runs1 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 votes2094 runs0 comment

Which statement(s) is/are true about the `localStorage` API?

Front-end developer
javascript
api
storage
Jean-marie Cléryat Jan 4, 2022
Hard
3 votes2080 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 votes2072 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
Hard
3 votes2067 runs0 comment

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

Front-end developer
inheritance
prototype
constructor
Jean-marie Cléryat Jan 4, 2022
Medium
3 votes269 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 votes220 runs0 comment

Compare two numbers in Javascript

Front-end developer
equality
comparison
type
Vincent Cotroat Sep 19, 2022
Hard
2 votes2112 runs1 comment

Which statements are true about JavaScript Strict Mode?

Front-end developer
javascript
strict mode
Jean-marie Cléryat Jan 4, 2022
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