JavaScript Interview Questions
JavaScript is the foundation of web development and one of the most tested languages in technical interviews. These questions span the concepts that interviewers consistently ask — from closure mechanics and the event loop to advanced patterns like generators and proxies. Whether you're targeting frontend, backend (Node.js), or full-stack roles, mastering these topics will set you apart.
Core Concepts
JavaScript Closures — How They Work and Why They Matter
What is a closure in JavaScript? Can you give a practical example of when you'd use one?
Prototypal Inheritance in JavaScript — How It Actually Works
How does prototypal inheritance work in JavaScript? How is it different from classical inheritance?
The 'this' Keyword in JavaScript — All the Rules
How does the 'this' keyword work in JavaScript? What are the rules that determine its value?
Async Patterns
The JavaScript Event Loop — How Async Code Actually Works
Explain how the JavaScript event loop works. What's the difference between the task queue and the microtask queue?
Promises and Async/Await in JavaScript — Complete Guide
Explain how Promises work. How does async/await relate to Promises? How do you handle errors?