Esbuild serve and reload

build.mjs

import esbuild from "esbuild";
import { createServer } from "http";

const clients = [];

esbuild
  .build({
    entryPoints: ["./index.tsx"],
    bundle: true,
    outfile: "bundle.js",
    banner: {
      js: ' (() => new EventSource("http://localhost:8000").onmessage = () => location.reload())();',
    },
    watch: {
      onRebuild(error) {
        clients.forEach((res) => res.write("data: update\n\n"));
        clients.length = 0;
        console.log(error ? error : "...");
      },
    },
  })
  .catch(() => process.exit(1));

createServer((req, res) => {
  return clients.push(
    res.writeHead(200, {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache",
      "Access-Control-Allow-Origin": "*",
      Connection: "keep-alive",
    }),
  );
}).listen(8000);