Top 30 JavaScript Interview Questions and Answers for Technical Leads (2026)
JavaScript remains the foundation of modern web and hybrid mobile application development. Whether you're preparing for a Technical Lead, Senior Developer, Angular, Ionic, React, or Full Stack interview, mastering these core JavaScript concepts is essential. This guide covers the most frequently asked JavaScript interview questions along with concise professional answers. 1. What is the difference between var, let, and const? Feature| var| let| const Scope| Function| Block| Block Reassignment| Yes| Yes| No Redeclaration| Yes| No| No Hoisting| Yes| Yes| Yes Best Practice: Prefer "const" by default and use "let" only when reassignment is required. --- 2. What is Hoisting? Hoisting is JavaScript's behavior of moving variable and function declarations to the top of their scope during compilation. console.log(a); var a = 10; Output: undefined --- 3. What is a Closure? A closure allows a function to access variables from its outer scope even after the outer functi...