JavaScript

JavaScript is a dynamically-typed, single-threaded, event-driven language that runs in browsers and on the server via Node.js (and alternatives like Deno and Bun). It is the only language that runs natively in every web browser, and its non-blocking I/O model makes it well-suited for high-concurrency backend services.

Notes

• js_core_language — types, variables, coercions, truthy/falsy, template literals
• js_functions — declarations vs expressions, arrow functions, closures, scope, this, error handling
• js_objects_and_classes — object literals, spread/destructure, optional chaining, prototypes, classes, inheritance
• js_collections — arrays, maps, sets, and all loop constructs (for, for...of, for...in, while)
• js_async — event loop, call stack, task queue, microtask queue, Promises, async/await
• js_modules — CommonJS, ES Modules, "type": "module", bundlers (Webpack, Vite, Rollup)
• js_runtimes — Node.js, npm, Deno, Bun comparison, polyfills, transpilers