JavaScript Interview Questions

Hi there! If you are preparing for web developer interview questions on JavaScript, you are at the right place. So, these JavaScript interview questions and these unique interview questions to ask an employer will help you to stand out from other candidates.

Strategic interview questions, situational interview questions, ES6 features-related interview questions, best interview questions for DOM methods, and more.

This tool is ideal for individuals attempting to evaluate their abilities or those administering assessments to their staff. There is no jargon involved—only clear, practical insights.

Also check: JavaScript Cheat Sheet

Let’s jump in!

Beginner Level JavaScript Interview Questions

1. What is JavaScript?
JavaScript is a programming language that runs in the browser.

2. What does JS stand for?
It stands for JavaScript.

3. What is the difference between var, let, and const?
var is function-scoped; let and const are block-scoped. const cannot be reassigned.

4. What is an arrow function?
It’s a shorter syntax for a function using =>.

5. What is a closure?
A closure is a function that has access to its scope and outer scopes.

6. What is the DOM?
The DOM is a tree of objects that represents the web page.

7. How do you select an element by ID?
Use document.getElementById(“id”).

8. What is a bubbling event?
It’s when an event starts with a child and moves up to parents.

9. What is the difference between == and ===?
== checks value with conversion. === checks value and type.

10. What is NaN?
NaN means Not-a-Number. It is a special numeric value.

11. What is a promise?
A promise is an object for async tasks. It can succeed or fail.

12. What is async/await?
They are syntax to work with promises more simply.

13. What is hoisting?
Hoisting moves variable and function declarations to the top.

14. What is a prototype in JS?
The prototype is an object that lets other objects inherit features.

15. What is the use of strict mode?
Strict mode catches common mistakes and unsafe actions.

16. What is JSON?
JSON is a text format for data. It looks like JS objects.

17. What is localStorage?
It lets you store data in the browser that stays after a reload.

18. What is an IIFE?
It’s an Immediately Invoked Function Expression that runs right away.

19. What are call, apply, and bind?
They set this value in functions in different ways.

20. What is the difference between synchronous and asynchronous code?
Synchronous runs in order, one after the other. Asynchronous can run later or in the background.

Check: JavaScript roadmap

Final Thoughts

That’s a wrap! These JavaScript questions guide the approach to web developer interview questions. For that purpose, use the best interview questions, situational interview questions, and many others.

Choose those that fit your role. You’ve got this! I wish you good luck, and do not hesitate to ask your employer unusual questions.