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Introduction to JavaScript

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JavaScript is the language of the web — every browser ships with a JS engine, and Node.js lets the same language run on servers, build tools, and CLIs. It's dynamically typed, single-threaded but asynchronous, and the most-used programming language on the planet. You can start writing it in any browser's DevTools console — no install, no compiler.

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Detailed Theory

# Introduction to JavaScript

What it is

  • Created: 1995 by Brendan Eich at Netscape — in *10 days*.
  • Standard: ECMAScript (ES). The yearly release cadence (ES2015 a.k.a. ES6 was the big one) keeps adding features.
  • Engines: V8 (Chrome, Node.js, Edge), SpiderMonkey (Firefox), JavaScriptCore (Safari).
  • Where it runs:
- Browser — DOM manipulation, events, fetch, animations. - Node.js — servers, build tools, CLIs, scripts. - Embedded — desktop apps via Electron/Tauri, mobile via React Native, even microcontrollers.

The 30-second history

  • 1995 — JavaScript ships in Netscape Navigator.
  • 1997 — standardised as ECMAScript.
  • 2009 — Node.js puts JS on servers.
  • 2015 — ES6 / ES2015 — let, const, arrow functions, classes, modules, Promises. *The* modern-JS turning point.
  • 2017 — async / await.
  • 2024+ — yearly releases, top-level await, decorators, pattern-matching proposals.

Three ways to run it

1. Browser DevTools console

Right-click anywhere → Inspect → Console tab. Type: 
console.log("hello, world");
1 + 2 * 3;     // → 7

2.