JavaScript in depth
The event loop, closures, async and the coding round.
- JS.01The event looppredict the order of any mix of sync code, promises, timers, rendering and Node callbacks.7 concepts · 7 ready
- JS.02Scope, hoisting and closuresexplain lexical scope and closures from the spec model and use them deliberately.5 concepts · 5 ready
- JS.03this, call, apply and binddetermine `this` in any call and control it.3 concepts · 3 ready
- JS.04Prototypes and classesexplain the prototype chain and how classes are built on it.4 concepts · 3 ready
- JS.05Types, values and coercionpredict type conversion and equality, and handle numbers correctly.5 concepts · 4 ready
- JS.06Objects, collections and copyingchoose the right collection and copy data correctly.4 concepts · 2 ready
- JS.07Functions in depthuse higher-order functions, currying, memoization, recursion and generators confidently.5 concepts · 4 ready
- JS.08Modern JavaScript (ES2015 → ES2026)know and use modern syntax and APIs; know what is new and when it landed.4 concepts · 2 ready
- JS.09Regular expressionsread, write and test regexes for validation and parsing.2 concepts
- JS.10Modulesunderstand ES modules vs CommonJS and how bundlers use them.4 concepts · 3 ready
- JS.11Async in depthimplement and reason about promises, combinators, cancellation, races, retries and concurrency.8 concepts · 7 ready
- JS.12V8 and memory basicsreason about JIT performance, object shapes and garbage collection at an interview level.4 concepts · 2 ready
- JS.13Errors and debugging in depthproduce useful errors and debug production JavaScript.2 concepts · 2 ready
- JS.14The coding round I: method and function utilitiessolve "implement X" questions with a reliable method; master function utilities.6 concepts
- JS.15The coding round II: polyfillsimplement core language and library features from scratch, matching the spec's important edge cases.7 concepts
- JS.16The coding round III: data structures and patternsimplement the classic utility and pattern questions (with JS.14 and JS.15, at least 35 implementations).12 concepts