JavaScript Engine and Basics
Target Version: ECMAScript 2023+ (ES14+) Official Documentation: MDN JavaScript Guide
1. Introduction to JavaScript
An essential language for modern web development. Created in 10 days by Brendan Eich in 1995, it has expanded from the client (browser) to the server (Node.js) domain.
- Features: First-class functions, prototype-based inheritance, single-threaded asynchronous processing.
- Advantages: Runs in all browsers and has the world's most active community (npm).
- Core Engines: Chrome's V8, Firefox's SpiderMonkey, Safari's JavaScriptCore.
2. Hello, World! (Console Learning)
Try running this directly in your browser's developer tools (F12) Console tab.
// Modern variable declaration (const, let recommended)
const message = "Hello, JavaScript!";
console.log(message);
// Arrow Function
const multiply = (a, b) => a * b;
console.log(`10 * 20 = ${multiply(10, 20)}`);
3. Core Basic Syntax
- Variable Declaration:
const(immutable),let(mutable, block-scoped). - Data Types: Number, String, Boolean, Object, undefined, null.
- Asynchronous Processing: Promise-based logic processing via
async / await. - Module Systems: ESM (
import / export), CommonJS (require).