JS interview question with answer 2024.

  • What is JavaScript, and what are its key features?
  • JavaScript is a high-level, interpreted programming language that is used to make web pages interactive and dynamic. Its key features include being lightweight, versatile, and supporting functional and object-oriented programming paradigms.
  • Explain the difference between “undefined” and “null” in JavaScript.
  • “undefined” means a variable has been declared but has not been assigned a value, while “null” is an assignment value that represents the absence of a value.
  • What is the difference between “==” and “===” in JavaScript?
  • “==” checks for equality of values, while “===” checks for equality of values and data types.
  • How does JavaScript handle asynchronous operations?
  • JavaScript uses callbacks, promises, and async/await to handle asynchronous operations.
  • Explain the concept of hoisting in JavaScript.
  • Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their containing scope during the compilation phase.
  • What are the different data types in JavaScript?
  • JavaScript has six primitive data types: string, number, boolean, null, undefined, and symbol; and one complex data type, which is object.
  • How can you handle errors in JavaScript?
  • Errors in JavaScript can be handled using try-catch blocks, throwing custom errors, and using the “finally” block to execute code after try and catch regardless of the result.
  • What is the use of the “this” keyword in JavaScript?
  • The “this” keyword refers to the object it belongs to and is used to access object properties and methods within the object.
  • Explain the concept of closures in JavaScript.
  • Closures are functions that have access to the outer function’s scope even after the outer function has finished executing.
  • What are the different ways to create an object in JavaScript?
  • Objects in JavaScript can be created using object literals, constructor functions, and the “class” keyword introduced in ES6.

About Vijay Dhanvai

A passionate blogger by heart and mind, I have been working in this field for 10 years now. A WordPress Professional, web developer and designer who intends to guide his readers about Web Design, WordPress, Blogging, Web Development, and more.

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