+- Anna University Plus (https://annauniversityplus.com)
+-- Forum: Career & Placement Zone (https://annauniversityplus.com/Forum-career-placement-zone)
+--- Forum: Interview Prep (https://annauniversityplus.com/Forum-interview-prep)
+--- Thread: JavaScript Interview Questions and Answers 2026 - Top 10 JS Questions (/javascript-interview-questions-and-answers-2026-top-10-js-questions)
JavaScript Interview Questions and Answers 2026 - Top 10 JS Questions - Admin - 03-21-2026
JavaScript is the most popular programming language in 2026 and is essential for frontend, backend, and full-stack development. Whether you are applying for a Frontend Developer, Full-Stack Engineer, or Web Developer role, these top 10 JavaScript interview questions will help you prepare and succeed.
Keywords: JavaScript interview questions 2026, JS coding interview, frontend developer interview, ES6 interview questions, web development interview prep
1. What is the difference between var, let, and const?
var is function-scoped and can be redeclared. let is block-scoped and can be reassigned but not redeclared. const is block-scoped and cannot be reassigned or redeclared. Always prefer const for values that do not change and let for variables that need reassignment.
2. Explain closures in JavaScript.
A closure is a function that remembers its outer scope variables even after the outer function has finished executing. Closures are used for data privacy, event handlers, and callback functions. They are fundamental to functional programming in JavaScript.
3. What is the event loop in JavaScript?
The event loop manages asynchronous operations in JavaScript. It continuously checks the call stack and callback queue. When the call stack is empty, it pushes the first callback from the queue onto the stack. This enables non-blocking I/O operations.
4. What are Promises and async/await?
Promises represent the eventual completion or failure of an asynchronous operation. They have three states: pending, fulfilled, and rejected. async/await is syntactic sugar over Promises that makes asynchronous code look synchronous and easier to read and debug.
5. Explain prototypal inheritance in JavaScript.
JavaScript uses prototypal inheritance where objects inherit directly from other objects. Every object has a prototype chain. When a property is accessed, JavaScript looks up the prototype chain until it finds the property or reaches null. ES6 classes are syntactic sugar over prototypes.
6. What is hoisting in JavaScript?
Hoisting is JavaScript's behavior of moving variable and function declarations to the top of their scope during compilation. var declarations are hoisted and initialized as undefined. let and const are hoisted but remain in a temporal dead zone until their declaration is reached.
7. What are higher-order functions?
Higher-order functions are functions that take other functions as arguments or return functions. Common examples include map, filter, reduce, forEach, and sort. They enable functional programming patterns and make code more declarative and reusable.
8. Explain the difference between == and ===.
== performs type coercion before comparison, meaning it converts operands to the same type. === performs strict comparison without type coercion, checking both value and type. Always prefer === to avoid unexpected type conversion bugs.
9. What is the spread operator and destructuring?
The spread operator (...) expands arrays or objects into individual elements. Destructuring allows extracting values from arrays or properties from objects into distinct variables. Both are ES6 features that make code cleaner and more readable.
10. What are Web APIs and how does fetch work?
Web APIs are browser-provided interfaces like DOM, fetch, localStorage, and setTimeout. The fetch API is used to make HTTP requests and returns a Promise. It supports GET, POST, PUT, DELETE methods and is the modern replacement for XMLHttpRequest.
Conclusion: JavaScript remains the backbone of web development. Master these core concepts, practice coding challenges, and understand ES6+ features to ace your next JavaScript interview.
Tags: #JavaScript #InterviewQuestions #WebDevelopment #Frontend #ES6 #ReactJS #NodeJS #FullStack #JSInterview #CodingInterview2026