@justscale/sse

Server-Sent Events for JustScale. Register an SSE route that yields events to an HTTP client as an async generator.

Install

pnpm add @justscale/sse

Usage

import { SSE } from '@justscale/sse';
import { createController, EventBus } from '@justscale/core';

createController({
  inject: { bus: EventBus },
  routes: ({ bus }) => ({
    events: SSE('/events')
      .handle(async function* () {
        for await (const event of bus.subscribe('*')) {
          yield { event: event.type, data: event.payload };
        }
      }),
  }),
});

The handler is a generator — yield { event, data } sends an SSE frame, returning ends the stream, throwing sends an error event and closes. Heartbeats are emitted automatically. SSE routes are registered through @justscale/http's request-handler chain, so they sit on the same port as the rest of the HTTP surface.

Docs

https://justscale.sh/features/datastar (Datastar rides on top of SSE for reactive streaming.)