9 Tips to Prepare for Javascript Interview Questions.

Javascript Interview Questions


JavaScript is a popular and versatile programming language used to create dynamic websites and applications. When it comes to JavaScript interview Questions, it’s essential to be familiar with the language and to be able to answer questions about it. To help you prepare for your next JavaScript interview, here are 20 common questions you should be prepared to answer.

Preparing for Your JavaScript Interview Questions

Before your JavaScript interview, it’s important to thoroughly familiarize yourself with the language. You could start by reading a JavaScript guide or taking a course. It’s also beneficial to practice solving coding challenges and take any open-source JavaScript projects or internships. When it comes to preparing, here are some things to keep in mind:

  • Understand the basic principles of JavaScript.
  • Learn the syntax, core concepts, and features of the language.
  • Know how to use JavaScript for web development.
  • Be familiar with the Document Object Model and working with events and event delegation.
  • Be able to leverage APIs to retrieve data.
  • Know how to troubleshoot and debug common JavaScript errors.
  • Understand the principles of performance optimization.
  • Be able to utilize design patterns and regular expressions.
  • Know how to work with variables, loops, and control structures.

Commonly Asked Questions During JavaScript Interviews

During your JavaScript interview, you may be asked a range of questions so that the interviewer can see your level of understanding and familiarity with the language. Let’s consider some of the most common questions you may encounter.

What is JavaScript?

You should expect to be asked to explain what is JavaScript, and how it’s different from other programming languages. JavaScript is a client-side scripting language used to create dynamic web pages and applications. It is one of the primary languages used for web development, along with HTML and CSS.

Unlike HTML and CSS, which simply provide structure and styling to web pages, JavaScript acts as an interactive layer on the page, creating experiences like live updates and animation. JavaScript is also different than other programming languages in that it’s based on a prototype-based, object-oriented programming model, which is highly flexible and extensible.

What is the programming syntax of JavaScript?

The JavaScript language has a simple syntax, making it relatively easy to learn. It uses JavaScript objects, and it is object-oriented. The syntax consists of statements, variables, identifiers, operators, functions, and other programming elements.

How to understand and use control structures?

In programming, control structures are used to control the order of program execution. In JavaScript, these structures are known as conditional statements or loops. They allow you to control whether a particular statement or block of code is executed or not. You should be familiar with the “if”, “else”, “while”, “for”, and “switch” statements, as well as their syntax and usage.

What are the core concepts of JavaScript?

The core concepts of JavaScript include objects, functions, events, DOM (Document Object Model), and AJAX (Asynchronous JavaScript and XML). These are fundamental concepts to any JavaScript-based application.

How to troubleshoot common JavaScript errors?

When developing with JavaScript, you will inevitably run into errors. It’s important to be able to identify the source of the errors, as well as how to correct them. Common errors include syntax errors, reference errors, logic errors, and “undefined” errors. You should be familiar with the different types of errors, as well as how to troubleshoot and debug them.


Preparing for a JavaScript interview is no easy task, but with the right preparation and practice, you can ace it. Knowing the answers to common JavaScript interview questions and understanding the different aspects of the language are essential for succeeding in your interview. With this knowledge, you are sure to impress your interviewer and land the job.


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