esbuild.config.js

#!/usr/bin/env node

const esbuild = require('esbuild')
const path = require('path')

// Add more entrypoints, if needed
const entryPoints = [
    "application.js",
]
const watchDirectories = [
    "./app/javascript/**/*.js",
    "./app/views/**/*.html.erb",
    "./app/assets/stylesheets/*.css",
    "./app/assets/stylesheets/*.scss"
]

const config = {
    absWorkingDir: path.join(process.cwd(), "app/javascript"),
    bundle: true,
    entryPoints: entryPoints,
    outdir: path.join(process.cwd(), "app/assets/builds"),
    sourcemap: true
}

async function rebuild() {
    const chokidar = require('chokidar')
    const http = require('http')
    const clients = []

    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);

    let result = await esbuild.build({
        ...config,
        incremental: true,
        banner: {
            js: ' (() => new EventSource("http://localhost:8082").onmessage = () => location.reload())();',
        },
    })

    chokidar.watch(watchDirectories).on('all', (event, path) => {
        if (path.includes("javascript")) {
            result.rebuild()
        }
        clients.forEach((res) => res.write('data: update\n\n'))
        clients.length = 0
    });
}

if (process.argv.includes("--rebuild")) {
    rebuild()
} else {
    esbuild.build({
        ...config,
        minify: process.env.RAILS_ENV == "production",
    }).catch(() => process.exit(1));
}