JavaScript

JavaScript ES6+ — Arrow Functions / Destructuring / Spread / Modules

Professional · priority 1

javascriptes6arrow-functionsdestructuringspreadmodulestemplate-literals

Async/Await & Promises — Asynchronous JavaScript Mastery

Professional · priority 1

javascriptasyncawaitpromisefetchaxioserror-handling

let / const / var — Hoisting, TDZ, Scope Pitfalls in Real Codebases

Professional · priority 1

javascriptletconstvarhoistingtdzscope

Closures & this — Arrow vs Function, bind/call/apply, Event Handlers

Professional · priority 1

javascriptclosurethisarrowbindcallapply

Promises & async/await — Error Propagation, Sequencing, Race Conditions

Professional · priority 1

javascriptpromiseasyncawaitraceerror-handling

fetch & AbortController — Timeouts, Retries, Streaming, Cancellation

Professional · priority 1

javascriptfetchabortcontrollertimeoutstreamingcancel

Array Methods — map / filter / reduce / flatMap / findIndex Patterns

Professional · priority 1

javascriptarraymapfilterreduceflatmap

Destructuring & Spread — Rest Params, Nested Defaults, API Shapes

Professional · priority 1

javascriptdestructuringspreadrestdefaults

ESM vs CommonJS — package.json exports, Dual Publish, Tree Shaking

Professional · priority 1

javascriptesmcommonjsexportsdual-publishtree-shaking

Testing — vitest / jest / playwright, Test Doubles, Fake Timers

Professional · priority 1

javascriptvitestjestplaywrightmockfaketimers