JavaScript — Interview questions
Arrays & Collections
Array methods and mutation, sort and copy semantics, Map and Set, WeakMap and WeakSet, typed arrays, and sparse arrays.
13 questions
Asynchronous JavaScript
Callbacks, promises and combinators, async/await, error handling, and observables.
12 questions
Browser & BOM
The BOM, navigation and page lifecycle, same-origin policy, timers, web storage, and web workers.
11 questions
CSS & Styling
CSS fundamentals for front-end work — the box model, spacing with gap, selector specificity, CSS-in-JS, and design tokens.
5 questions
Coding Tasks
Practical algorithm and closure tasks — arrays, strings, recursion, method chaining, and output prediction.
19 questions
Async Coding Tasks
Practical async tasks — promisify, promise combinators, event emitters, fetch retry, polling, and serialized writes.
9 questions
Coercion & Operators
Type and boolean coercion, loose vs strict equality, and the operator families — logical, bitwise, unary.
10 questions
DOM & Browser
The DOM — selection and manipulation, attributes vs properties, event handling, propagation, and custom elements.
8 questions
ES6+ Features
Classes, modules, template literals, destructuring, spread/rest, default parameters, dynamic imports, optional chaining, and nullish coalescing.
13 questions
Error Handling
try/catch/finally, throwing, the Error object and its subtypes, custom errors, strict mode, and asynchronous error handling.
12 questions
Event Loop & Iteration
The event loop, micro/macrotasks, iterators and iterables, generators, and reactive streams.
8 questions
Functional Programming
Pure functions, currying, partial application, composition, memoization, mixins, and function arity.
11 questions
Functions
Core functions — first-class and higher-order functions, closures, this-binding, arrow functions, and call/apply/bind.
10 questions
JSON & Data
JSON syntax and rules, JSON.stringify and JSON.parse with replacer/reviver, deep cloning, structuredClone, and the dangers of eval.
10 questions
Networking & HTTP
Web networking for front-end engineers — the HTTP request/response model, HTTP/2 multiplexing, and REST API design.
8 questions
Node.js
Server-side JavaScript with Node.js — when it fits, streams and backpressure, multi-core concurrency, and graceful shutdown.
5 questions
Objects & Prototypes
Objects — creation, copying, enumeration, property order, accessors, and property descriptors.
11 questions
Design Patterns
Classic design patterns in JavaScript — factory functions, the abstract factory, and the decorator, implemented with closures and ES6 classes.
3 questions
Prototypes & Inheritance
The prototype chain, __proto__ vs prototype, prototypal inheritance, extensibility, and Proxy.
10 questions
React & Redux
React fundamentals — components, hooks, state and effects, lifecycle, rendering, controlled inputs, and keys.
15 questions
Advanced React & Redux
Refs, context, memoization, HOC/render-props patterns, and the Redux data flow, middleware, normalization, and selectors.
12 questions
Scope & Hoisting
var/let/const, hoisting, the temporal dead zone, lexical and block scope, execution context, and variable shadowing.
12 questions
Strings & Regex
String methods, template literals, immutability, comparison, and regular expressions with their flags and methods.
12 questions
Engine & Tooling
The JS engine (V8, JIT, hidden classes), transpilation (Babel), bundling and tree-shaking, module systems (CommonJS vs ESM), runtimes (Node/Deno), and polyfills.
12 questions
Type System
Primitive types, typeof, null vs undefined, NaN, value vs reference, wrapper objects, and immutability.
8 questions
Web Fundamentals
Cross-cutting web knowledge for front-end engineers — image formats, network protocols, accessibility, component testing, and headless UI kits.
5 questions
Web Platform & APIs
Browser platform APIs — fetch and XHR, client storage and IndexedDB, web and service workers, postMessage, server-sent events, and PWAs.
12 questions
