esbuild config file with live reloading for rails

build.js

#!/usr/bin/env node

import esbuild from "esbuild"
import chokidar from "chokidar"
import http from "http"

const watchDirectories = [
  "./app/assets/builds/*",
  "./app/views/**/*.erb",
]
const watch = process.argv.includes("--watch")
const clients = []

const config = {
  entryPoints: ["app/assets/javascript/application.js"],
  bundle: true,
  outdir: "app/assets/builds",
  watch: watch,
  banner: {
    js: ' (() => new EventSource("http://localhost:8082").onmessage = () => location.reload())();',
  },
}

if (watch) {
  (async () => {
    await esbuild.build(config);
    chokidar.watch(watchDirectories).on('all', (event, path) => {
      console.log(`rebuilding ${path}`)
      clients.forEach((res) => res.write('data: update\n\n'))
      clients.length = 0
    })
  })();

  http.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(8082);

} else {
  esbuild
    .build(config)
    .catch(error => {
      console.log(error)
      process.exit(1)
    })
}

// Anything Vendor related
esbuild.build({
  entryPoints: ["vendor/blazer/javascript/application.js"],
  bundle: true,
  outfile: "app/assets/builds/blazer/application.js",
  watch: process.argv.includes("--watch")
}).catch(error => {
  console.log(error)
  process.exit(1)
})