broadcastChannel · @awacloud/fw

API pages

BroadcastChannel — cross-tab / cross-worker communication within the same origin.

Module broadcastChannel | Source packages/front/fw/src/dom/net/broadcastChannel.js | Deps none | Worker-safe yes

Minimal wrapper around the native BroadcastChannel API. Enables communication between tabs, workers, and service workers sharing the same origin. For command-based routing, see processMessage.

Resolve

const broadcastChannel = runtime.resolve('broadcastChannel');
// Returns: { create, isSupported }

API

Method	Signature	Returns
`create`	`(name: string) => Channel`	Channel instance
`isSupported`	`() => boolean`	`true` if `BroadcastChannel` is available

`Channel` object

Method / Property	Signature	Description
`post`	`(data: any) => void`	Sends a message (structured-cloneable)
`on`	`(callback: (data, event) => void) => () => void`	Adds a listener; returns unsubscribe
`off`	`(callback) => void`	Removes a listener
`close`	`() => void`	Closes the channel and removes all listeners
`name`	`getter: string`	Channel name

Semantics:

post is not received by the same instance — only by other instances with the same name.
Each call to create(name) returns a new independent instance.
close() releases resources and stops reception for this instance only.

Examples

Cross-tab communication

// Tab A
const broadcastChannel = runtime.resolve('broadcastChannel');
const ch = broadcastChannel.create('notifications');

ch.post({ type: 'reload', version: '2.1.0' });
ch.close();

// Tab B (same origin)
const ch = broadcastChannel.create('notifications');
const unsub = ch.on((data) => {
    if (data.type === 'reload') location.reload();
});

// Cleanup
window.addEventListener('unload', unsub);

Multiple listeners

const ch = broadcastChannel.create('sync');

const unsub1 = ch.on((data) => updateUI(data));
const unsub2 = ch.on((data) => logEvent(data));

// Remove a specific listener
unsub1();

Worker Usage

BroadcastChannel is available in Web Workers, SharedWorkers, and ServiceWorkers.

const worker = fw.createWorker(
    function ({ libs, args }) {
        const ch = libs.broadcastChannel.create(args.channelName);
        ch.post({ status: 'done', result: computeResult() });
        ch.close();
    },
    { dependencies: ['broadcastChannel'], args: { channelName: 'worker-results' } }
);

Notes

Messages received in send order per channel, but inter-channel order is not guaranteed.
Data sent via structured clone — Function, Symbol, undefined are not transferable.
For message-type routing: wrap with a { type, payload } object and dispatch on the receiver side.
For RPC (request/response): processRPC.
isSupported() returns false in environments without BroadcastChannel (very old contexts).