Function startRspackWatch

utils/scripts/dev.js:313–382

(host, port, proto, onCompiled)

// ─── rspack watcher ──────────────────────────────────────────────────────────

function startRspackWatch(host, port, proto, onCompiled) {
	log("info", "Starting rspack --watch...");

	const env = buildSpawnEnv({
		DEV_MODE: "true",
		DEV_HOST: host,
		DEV_PORT: String(port),
		DEV_PROTO: proto,
	});
	const rspackBin = path.join(
		ROOT,
		"node_modules",
		"@rspack",
		"cli",
		"bin",
		"rspack.js",
	);

	const useLocalRspack = fs.existsSync(rspackBin);
	if (!useLocalRspack) {
		log("warn", "Local rspack CLI not found, falling back to npx rspack");
	}

	const proc = useLocalRspack
		? spawn(process.execPath, [rspackBin, "--watch", "--mode", "development"], {
				cwd: ROOT,
				env,
				stdio: "pipe",
			})
		: spawn(
				resolveSpawnCommand("npx"),
				["rspack", "--watch", "--mode", "development"],
				{
					cwd: ROOT,
					env,
					stdio: "pipe",
				},
			);

	let firstCompile = true;

	proc.stdout.on("data", (chunk) => {
		const text = chunk.toString();
		process.stdout.write(text);
		if (text.includes("compiled successfully") || text.includes("compiled")) {
			if (firstCompile) {
				firstCompile = false;
			}
			onCompiled();
		}
	});

	proc.stderr.on("data", (chunk) => {
		process.stderr.write(chunk);
	});

	proc.on("error", (err) => {
		log("warn", `rspack error: ${err.message}`);