PubSubJS

Why PubSubJS?

Type-Safe

Full TypeScript support with inferred types for events, payloads, and handlers. Catch errors at compile time.

Schema Validation

Validate payloads at runtime using Zod, Valibot, or any Standard Schema compatible library.

Transport Agnostic

Use WebSocket, Redis, SSE, or create your own transport. Switch transports without changing your code.

Middleware Support

Add logging, rate limiting, idempotency, and more with composable middleware for both publishing and subscribing.

Quick Example

import { z } from "zod";
import { defineEvent, Publisher, Subscriber } from "@pubsubjs/core";
import { WebSocketServerTransport } from "@pubsubjs/transport-websocket";

// Define type-safe events with schemas
const events = defineEvent([
  {
    name: "user.created",
    schema: z.object({
      userId: z.string(),
      email: z.string().email(),
    }),
  },
]);

// Create transport
const transport = new WebSocketServerTransport({ port: 8080 });

// Publish events
const publisher = new Publisher({ events, transport });
await publisher.publish("user.created", {
  userId: "123",
  email: "user@example.com",
});

// Subscribe to events
const subscriber = new Subscriber({ events, transport });
subscriber.on("user.created", (payload) => {
  console.log(`New user: ${payload.email}`);
});
await subscriber.subscribe();

Packages

Package	Description
@pubsubjs/core	Core pub/sub functionality, types, and middleware
@pubsubjs/transport-websocket	WebSocket transport for browser and server
@pubsubjs/transport-redis	Redis transport for distributed systems
@pubsubjs/transport-sse	Server-Sent Events transport
@pubsubjs/react	React hooks and components