randomString.js

// Return random string of given length.
// Use Math.random function.
function mathRandomString(length) {
	const set = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

	let result = "";
	for (let i = 0; i < length; i += 1) {
		result += set[Math.floor(Math.random() * set.length)];
	}

	return result;
}

// Return random string of given length.
// Use crypto.getRandomValues function.
function cryptoRandomString(length) {
	const set = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
	let randVals = new Uint32Array(length);
	crypto.getRandomValues(randVals);

	let result = "";
	for (let i = 0; i < length; i += 1) {
		result += set[randVals[i] % set.length];
	}

	return result;
}

// Print some.
for (let i = 0; i < 4; i += 1) {
	console.log(mathRandomString(32));
}

console.log();

for (let i = 0; i < 8; i += 1) {
	console.log(cryptoRandomString(32));
}