cloudflare-durable_object-sse.mjs

import { DurableObject } from "cloudflare:workers";

export default {
  /** @param {Request} request  */
  async fetch(request, env, ctx) {
    if(request.headers.get('Accept')!='text/event-stream'){
      return new Response()
    }
    let id = env.EVENT_SOURCE.idFromName('test');
    let stub = env.EVENT_SOURCE.get(id);
    return stub.fetch(request)
  }
};

// Durable Object
export class EventSource extends DurableObject {

  constructor(ctx, env) {
    super(ctx, env)
    this.ctx = ctx
    ctx.storage.setAlarm(Date.now()+45000)
  }

  async alarm(){
    const writer=this.encoderStream.writable.getWriter()
    writer.write(': keepalive \n\n')
    this.ctx.storage.setAlarm(Date.now()+45000)
  }

  async fetch(request) {
    this.encoderStream=new TextEncoderStream()
    return new Response(this.encoderStream.readable, {
      headers: {
        "Content-Type": "text/event-stream",
        "Cache-Control": "no-cache",
      }
    })
  }

  async send(data,event=undefined,id=undefined){
    const writer=this.encoderStream.writable.getWriter()
    if(event){
      writer.write('event: '+event+'\n')
    }
    if(id){
      writer.write('id: '+id+'\n')
    }
    for(const line of data.split('\n')){
      writer.write('data: '+line+'\n')
    }
    writer.write('\n')
  }
}