cloudflare-workers-sse

Elegant Server-Sent Events (SSE) steaming implementation for Cloudflare Workers.

• Offers a simple, straightforward, and functional approach to streaming events using async generators.
• Easily integrates with existing Workers.
• Works seamlessly with OpenAI streaming.

Installation

With npm

npm install cloudflare-workers-sse

With Yarn

yarn add cloudflare-workers-sse

With pnpm

pnpm add cloudflare-workers-sse

With Bun

bun add cloudflare-workers-sse

Usage

A worker implementation:

import { sse } from "cloudflare-workers-sse";

export default {
  fetch: sse(handle),
};

async function* handle(request: Request, env: Env, ctx: ExecutionContext) {
  yield {
    event: "greeting",
    data: { message: "Hello, World!" },
  };
}

And a sample client code consuming the events:

const eventSource = new EventSource("https://your-worker.com");
eventSource.addEventListener("greeting", (event) => {
  const data = JSON.parse(event.data);
  console.log(data);
});

Custom Headers

By default only essential headers such as "Content-Type", "Cache-Control", and "Connection" are set.

You can add additional headers using the customHeaders option.

Example:

sse(handle, {
  customHeaders: { "Access-Control-Allow-Origin": "*" },
});