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JavaScript terms

98 terms of 1552 total · page 1 of 5

⚡ From DOM manipulation to async superpowers

JavaScript has evolved from a scripting curiosity into a full-stack language powering browsers, servers, and everything in between. This category covers the language core — closures, prototypes, async patterns, the event loop, modern ES2024+ features — as well as runtime behaviour that trips up developers at every experience level. Understanding JavaScript deeply means fewer bugs and more confident code.

More on JavaScript history · 5 references · key concepts

History

JavaScript was created in 1995 by Brendan Eich at Netscape Communications as a lightweight scripting language for web browsers, initially called Mocha and later LiveScript before being renamed JavaScript for marketing reasons. For over a decade, JavaScript remained primarily a client-side tool for DOM manipulation and form validation, with inconsistent implementations across browsers and limited standardization. The introduction of XMLHttpRequest in Internet Explorer 5 (1999) and subsequent AJAX adoption in the mid-2000s transformed JavaScript from a toy language into a serious platform for interactive web applications. The standardization of ECMAScript (ES5 in 2009) and major language improvements through ES2015 (ES6) and annual updates brought modern features like classes, promises, arrow functions, and modules, while the rise of Node.js (2009) extended JavaScript beyond browsers into server-side development. Today, JavaScript has evolved into a full-stack language with sophisticated tooling (bundlers, frameworks, type systems), widespread use in both frontend and backend, and a mature ecosystem that makes it one of the most widely-used programming languages in the world.

Key concepts

  • JavaScript Closures
  • JavaScript Event Loop
  • Hoisting — var
  • let
  • const and function
  • Promises & Promise Chaining
  • DOM Manipulation
  • ES Modules (import/export)
  • Async Error Handling (try/catch + Promise)
  • Type Coercion Gotchas (== vs ===)

Best references

  • MDN Web Docs — JavaScript Authoritative reference for all JavaScript APIs, language features, and DOM standards. Covers every term in this category with examples and browser compatibility.
  • ECMAScript Language Specification (ECMA-262) The official standard defining JavaScript syntax, types, and built-in objects. Essential for understanding the specification behind language features like async/await, modules, and error handling.
  • You Don't Know JS Yet (Kyle Simpson) Deep, practical treatment of closures, scope, hoisting, prototypes, async patterns, and type coercion—foundational concepts underpinning many glossary terms.
  • JavaScript.info Comprehensive tutorial covering modern JavaScript from fundamentals through advanced topics like Promises, Generators, and the Event Loop with interactive examples.
  • Web APIs — MDN Complete reference for browser APIs (Fetch, Canvas, Geolocation, Streams, MutationObserver, etc.) covered extensively in this category.
🧠 Logic graph · JavaScript
51 edges here
11 verbs used
55 terms touched
1 narrative
✦ Latest in JavaScript

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Edges touching a JavaScript term.

🤖 AI Guestbook — JavaScript educational data only
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Most referenced — JavaScript
package.json & npm — Alongside composer.json 2Page Visibility API 2Performance API & User Timing 2Fetch API 2navigator.sendBeacon 2CSRF Token Handling in Fetch & Axios 1DOM Manipulation 1Temporal Dead Zone (TDZ) 1
Page Visibility API 2Functional Array Methods (JS) 1package.json & npm — Alongside composer.json 1Intl API 1Object.freeze / Object.seal 1Event Loop Blocking — Long Tasks 1Memory Leaks — Closures, Detached DOM 1ES Modules (import/export) 1
CSRF Token Handling in Fetch & Axios 269Page Visibility API 200Web Share API 151Custom Events & EventTarget API 147IndexedDB 139async/await 133navigator.sendBeacon 129Fetch API & HTTP Requests 128
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navigator.sendBeacon ES2015
navigator.sendBeacon queues a small asynchronous POST that survives page unload, designed for analytics and diagnostic pings.
2mo ago JavaScript intermediate
Object Property Descriptors ES5
Property descriptors define the hidden attributes of object properties - writable, enumerable, configurable, plus getters and setters.
4mo ago JavaScript advanced
JavaScript Proxy Object ES2015
Proxy wraps an object to intercept fundamental operations like property access, assignment, and function calls via trap handlers.
5mo ago JavaScript advanced
async / await in JavaScript ES2017 🧠 5
async functions always return a Promise; await pauses execution inside an async function until a Promise settles — giving asynchronous code the readability of synchronous code without blocking the event loop.
6mo ago JavaScript intermediate
ES Modules (ESM) ES2015
The official JavaScript module system — import and export statements enable static dependency graphs, tree-shaking, and native browser module loading without a bundler.
6mo ago JavaScript intermediate
Fetch API ES2015 🧠 2
The browser-native Promise-based API for making HTTP requests — replacing XMLHttpRequest with a cleaner interface supporting streaming, CORS, and request/response objects.
6mo ago JavaScript beginner
Memory Management in JavaScript
JavaScript uses automatic garbage collection — the engine reclaims memory when objects are no longer reachable. Memory leaks occur when references are unintentionally retained, preventing collection.
6mo ago JavaScript intermediate
Array.flat() & Array.flatMap() ES2019 🧠 1
Array.flat(depth) flattens nested arrays; Array.flatMap() maps then flattens one level — more efficient than map().flat() and great for expanding items.
7mo ago JavaScript beginner
BigInt — Arbitrary Precision Integers ES2020
JavaScript's Number type cannot safely represent integers larger than 2⁵³−1 (Number.MAX_SAFE_INTEGER). BigInt is a separate numeric type that handles integers of arbitrary size, essential for working with 64-bit IDs from databases, cryptographic values, and precise financial calculations.
7mo ago JavaScript intermediate
BroadcastChannel — Cross-Tab Messaging HTML5
BroadcastChannel allows same-origin pages/tabs to communicate — post a message on one tab, receive it in all others — without a server or service worker.
7mo ago JavaScript intermediate
Canvas API — 2D Drawing HTML5
The HTML Canvas API provides a 2D drawing surface via JavaScript — used for charts, image manipulation, games, data visualisations, and any pixel-level rendering that DOM elements cannot efficiently handle.
7mo ago JavaScript intermediate
Clipboard API HTML5 🧠 1
The async Clipboard API (navigator.clipboard) is the modern replacement for document.execCommand('copy') — supports text, images, and rich content with proper permission handling.
7mo ago JavaScript beginner
Error.cause — Error Chaining ES2022 🧠 2
ES2022 added a cause option to the Error constructor — 'new Error('message', { cause: originalError })' — enabling proper error chaining where a high-level error wraps its underlying cause, preserving the full error context across abstraction layers.
7mo ago JavaScript beginner
EventSource API — Server-Sent Events (Client Side) HTML5
EventSource is the browser API for consuming Server-Sent Events (SSE) — a one-directional server-to-client stream over HTTP that automatically reconnects, ideal for live feeds, notifications, and streaming LLM responses.
7mo ago JavaScript intermediate
Geolocation API HTML5
navigator.geolocation provides GPS/network location data — requires HTTPS, user permission, and graceful fallback handling for denial or unavailability.
7mo ago JavaScript beginner
Import Maps ES2020 🧠 2
Import maps let browsers resolve bare module specifiers (import 'lodash') without a bundler — mapping module names to URLs in a JSON script tag.
7mo ago JavaScript intermediate
IntersectionObserver API HTML5 🧠 1
IntersectionObserver fires when an element enters or leaves the viewport — the modern way to implement lazy loading, infinite scroll, and scroll-triggered animations.
7mo ago JavaScript intermediate
MutationObserver API HTML5 🧠 1
MutationObserver watches DOM tree changes — attribute changes, child additions/removals, text content changes — without polling or event listener on each node.
7mo ago JavaScript intermediate
Object.freeze / Object.seal ES5
Object.freeze() prevents all property changes (add/modify/delete), Object.seal() prevents add/delete but allows modification — both are shallow, not deep.
7mo ago JavaScript intermediate
Page Visibility API HTML5
The Page Visibility API tells you when a tab is hidden or visible — use it to pause animations, polls, and video when the user switches tabs.
7mo ago JavaScript beginner
✓ schema.org compliant