JavaScript Web_workers Guide
Web Workers run scripts in background threads without blocking the UI for CPU-intensive tasks. The guide walks through Basic Usage. `new Worker("worker.js")`. Post: `worker.postMessage(data)`. Receive: `worker.onmessage=event=>{}`. Terminate: `worker.terminate()`. Transfer: `postMessage(buf,[buf])` — zero-copy. Limitations: no DOM, limited APIs. Worker APIs: fetch, setTimeout, IndexedDB, WebAssembly. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.