example.js

document.body.innerHTML = `
	<pre id="history"></pre>
	<form>
	<input id="message" type="text">
	<button id="send">Send Message</button>
	</form>
	<p>Computing fibonacci without worker:</p>
	<input id="fib1" type="number">
	<pre id="output1"></pre>
	<p>Computing fibonacci with worker:</p>
	<input id="fib2" type="number">
	<pre id="output2"></pre>
`;

const history = document.getElementById("history");
const message = document.getElementById("message");
const send = document.getElementById("send");
const fib1 = document.getElementById("fib1");
const output1 = document.getElementById("output1");
const fib2 = document.getElementById("fib2");
const output2 = document.getElementById("output2");

/// CHAT with shared worker ///

const chatWorker = new SharedWorker(
	new URL("./chat-worker.js", import.meta.url),
	{
		name: "chat",
		type: "module"
	}
);

let historyTimeout;
const scheduleUpdateHistory = () => {
	clearTimeout(historyTimeout);
	historyTimeout = setTimeout(() => {
		chatWorker.port.postMessage({ type: "history" });
	}, 1000);
};
scheduleUpdateHistory();

const from = `User ${Math.floor(Math.random() * 10000)}`;

send.addEventListener("click", e => {
	chatWorker.port.postMessage({
		type: "message",
		content: message.value,
		from
	});
	message.value = "";
	message.focus();
	e.preventDefault();
});

chatWorker.port.onmessage = event => {
	const msg = event.data;
	switch (msg.type) {
		case "history":
			history.innerText = msg.history.join("\n");
			scheduleUpdateHistory();
			break;
	}
};

/// FIBONACCI without worker ///

fib1.addEventListener("change", async () => {
	try {
		const value = parseInt(fib1.value, 10);
		const { fibonacci } = await import("./fibonacci");
		const result = fibonacci(value);
		output1.innerText = `fib(${value}) = ${result}`;
	} catch (e) {
		output1.innerText = e.message;
	}
});

/// FIBONACCI with worker ///

const fibWorker = new Worker(new URL("./fib-worker.js", import.meta.url), {
	name: "fibonacci",
	type: "module"
	/* webpackEntryOptions: { filename: "workers/[name].js" } */
});

fib2.addEventListener("change", () => {
	try {
		const value = parseInt(fib2.value, 10);
		fibWorker.postMessage(`${value}`);
	} catch (e) {
		output2.innerText = e.message;
	}
});

fibWorker.onmessage = event => {
	output2.innerText = event.data;
};