JavaScript Broadcast_channel Guide
BroadcastChannel enables communication between same-origin browsing contexts (tabs, windows, iframes). The guide walks through Cross-Tab Communication. `new BroadcastChannel("channel")` — create/join. `.postMessage(data)` — send. `.onmessage=event=>{}` — receive. `.close()` — leave. Uses: sync state across tabs (logout, theme), coordinate shared resources, cross-tab data updates. 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.