Comprehensive list of JavaScript job interview topics

 Core JavaScript (Must-Know)

• Data Types & Type Coercion

• Variable Declarations (var, let, const)

• Scopes (Global, Function, Block)

• Hoisting

• Closures

• Promises / async-await

• Event Loop & Call Stack

• Memory Management & Garbage Collection

• Shallow vs Deep Copy

• Prototype & Prototypal Inheritance

• this keyword & binding (call, apply, bind)

• ES6+ Features:

  • Destructuring

  • Template literals

  • Arrow functions

  • Spread/Rest operators

  • Modules ( import/export)

  • Default parameters

  • Optional chaining (?.), nullish coalescing (??)

Advanced JavaScript

• Event Delegation

• Debouncing & Throttling

• Currying / Partial Application

• Functional Programming concepts

• Module Systems (CommonJS vs ES Modules)

• Factory vs Constructor Patterns

• Custom Iterators / Generators

• Symbol, Map, Set, WeakMap, WeakSet

• JavaScript Design Patterns (Singleton, Observer, Module, etc.)

Asynchronous JavaScript

• Callbacks vs Promises vs async/await

• Error Handling in async functions

• Promise.all / Promise.race / Promise.allSettled

• Microtasks vs Macrotasks

DOM and Browser APIs

• DOM Traversal & Manipulation

• Event Handling & Bubbling

• Forms and Validation

• LocalStorage, SessionStorage, Cookies

• Fetch API & XMLHttpRequest

• Web APIs:  setTimeout, setInterval, requestAnimationFrame

• Web Workers (basic understanding)

Performance Optimization

• Code splitting

• Lazy loading

• Tree shaking

• Minification & Bundling concepts

• Avoiding memory leaks

• Efficient DOM manipulation

Testing & Debugging

• Console & DevTools debugging

• Basic understanding of Unit testing (Jest/Mocha)

• Mocking async calls

• Writing testable JS code

Tooling & Ecosystem

• NPM/Yarn basics

• Webpack / Vite / Babel (basic knowledge)

• Linting & Formatting (ESLint, Prettier)

• Package.json structure

• Transpilation vs Compilation

Coding & Algorithm Questions

• Array & String manipulation

• Object operations

• Recursion

• Sorting & Searching

• Time and Space Complexity (Big-O Notation)

• Common DS problems:

  • Anagrams

  • Palindromes

  • Frequency counter

  • Sliding window

  • Two pointers

Framework-Specific 

• React.js / Node.js / Vue.js 

  • Component lifecycle

  • State management

  • Hooks (React)

  • Routing

  • SSR vs CSR

  • Express middleware (Node)