postaljs/postal.js

---

postaljs/postal.js.json

{
  "createdAt": "2011-10-27T04:40:05Z",
  "defaultBranch": "master",
  "description": "JavaScript pub/sub library supporting advanced subscription features, and several helpful add-ons.",
  "fullName": "postaljs/postal.js",
  "homepage": "http://ifandelse.com",
  "language": "TypeScript",
  "name": "postal.js",
  "pushedAt": "2026-03-21T19:59:11Z",
  "stargazersCount": 2835,
  "topics": [],
  "updatedAt": "2026-03-21T19:59:13Z",
  "url": "https://github.com/postaljs/postal.js"
}

postal

Pub/Sub message bus for JavaScript and TypeScript.

Features

• TypeScript-first — full type inference on channels, topics, and message data
• AMQP-style wildcards — * matches a single topic segment, # matches zero or more
• Channel-scoped messaging — isolate message domains with named channels
• Request/handle RPC — built-in request/response pattern
• Wire taps — global observers that see every message on the bus
• Transport system — bridge pub/sub across iframes, workers, and browser tabs
• Zero dependencies — no lodash, no nothing

Install

npm install postal

Quick Example

import { getChannel } from "postal";

const orders = getChannel("orders");

orders.subscribe("order.created", envelope => {
    console.log("New order:", envelope.payload.orderId);
});

orders.publish("order.created", { orderId: "abc-123" });

For the full API — wildcards, RPC, wire taps, transports — see the docs.

Upgrading from v2? postal v3 is a ground-up rewrite with breaking changes to the module system, subscriber callbacks, envelope shape, and more. See the v2 → v3 migration guide before upgrading.

Packages

Package	npm	Description
[postal]!(packages/postal/)	postal	Core message bus
[postal-transport-messageport]!(packages/postal-transport-messageport/)	postal-transport-messageport	MessagePort transport for iframes and workers
[postal-transport-broadcastchannel]!(packages/postal-transport-broadcastchannel/)	postal-transport-broadcastchannel	BroadcastChannel transport for cross-tab messaging
[postal-transport-serviceworker]!(packages/postal-transport-serviceworker/)	postal-transport-serviceworker	ServiceWorker transport — dedicated MessagePort per tab, presence tracking, SW restart resilience
[postal-transport-childprocess]!(packages/postal-transport-childprocess/)	postal-transport-childprocess	child_process/cluster IPC transport for Node.js

Development

pnpm install       # Install dependencies
pnpm build         # Build all packages
pnpm test          # Run all tests
pnpm lint          # Lint all packages
pnpm run checks    # lint + test + build (CI gate)

License

MIT