sashee/index.html

## index.html
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
</head>
<body>
  <script>
console.log = (msg) => document.body.innerText += `${msg}\n`;

// utility function for sleeping
const sleep = (n) => new Promise((res) => setTimeout(res, n));
(async () => {
  const double = (str) => {
  	return str + str;
  };

  console.log(double("abc"));
  // abcabc

  // https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest
  const digestMessage = async (message) => {
    const msgUint8 = new TextEncoder().encode(message);
    const hashBuffer = await crypto.subtle.digest("SHA-256", msgUint8);
    const hashArray = Array.from(new Uint8Array(hashBuffer));
    const hashHex = hashArray.map(b => b.toString(16).padStart(2, "0")).join('');
    return hashHex;
  };

  console.log(await digestMessage("msg"));
  // e46b320165eec91e6344fa10340d5b3208304d6cad29d0d5aed18466d1d9d80e
  const strings = ["msg1", "msg2", "msg3"];

  console.log(strings.map(double));
  // ["msg1msg1", "msg2msg2", "msg3msg3"]
  console.log(await strings.map(digestMessage));
  // [[object Promise],[object Promise],[object Promise]]

  console.log("\nfor iteration");
  // synchronous
  {
  	const res = [];
  	for (let i of [1, 2, 3]){
  		res.push(i + 1);
  	}
  	console.log(res);
  	// res: [2, 3, 4]
  }

  // asynchronous
  {
  	const res = [];
  	for (let i of [1, 2, 3]){
  		await sleep(10);
  		res.push(i + 1);
  	}
  	console.log(res);
  	// res: [2, 3, 4]
  }
})();
  </script>
</body>
</html>
	<!doctype html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	</head>
	<body>
	<script>
	console.log = (msg) => document.body.innerText += `${msg}\n`;

	// utility function for sleeping
	const sleep = (n) => new Promise((res) => setTimeout(res, n));
	(async () => {
	const double = (str) => {
	return str + str;
	};

	console.log(double("abc"));
	// abcabc

	// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest
	const digestMessage = async (message) => {
	const msgUint8 = new TextEncoder().encode(message);
	const hashBuffer = await crypto.subtle.digest("SHA-256", msgUint8);
	const hashArray = Array.from(new Uint8Array(hashBuffer));
	const hashHex = hashArray.map(b => b.toString(16).padStart(2, "0")).join('');
	return hashHex;
	};

	console.log(await digestMessage("msg"));
	// e46b320165eec91e6344fa10340d5b3208304d6cad29d0d5aed18466d1d9d80e
	const strings = ["msg1", "msg2", "msg3"];

	console.log(strings.map(double));
	// ["msg1msg1", "msg2msg2", "msg3msg3"]
	console.log(await strings.map(digestMessage));
	// [[object Promise],[object Promise],[object Promise]]

	console.log("\nfor iteration");
	// synchronous
	{
	const res = [];
	for (let i of [1, 2, 3]){
	res.push(i + 1);
	}
	console.log(res);
	// res: [2, 3, 4]
	}

	// asynchronous
	{
	const res = [];
	for (let i of [1, 2, 3]){
	await sleep(10);
	res.push(i + 1);
	}
	console.log(res);
	// res: [2, 3, 4]
	}
	})();
	</script>
	</body>
	</html>