uuid4 and maybe a valid uuid7 (aka tsid)

uuids.ts

const uuid4 = (): Uint8Array => {
	let res = crypto.getRandomValues(new Uint8Array(18));
	res[6] = (res[6] & 0x0f) | 0x40; // Version 4
	res[8] = (res[8] & 0x3f) | 0x80; // Variant is 10
	return res
};
const uuid7 = (() => {
	let prev = 0;
	return (): Uint8Array => {
		let res = uuid4();
		let now = Date.now() * 1000000;
		if (now <= prev) {
			now = prev + 1;
		}
		prev = now;
		const t = now >> 12;
		const s = now & 0xfff;
		// Set time bits.
		res[0] = t >> 40;
		res[1] = t >> 32;
		res[2] = t >> 24;
		res[3] = t >> 16;
		res[4] = t >> 8;
		res[5] = t;
		res[6] = 0x70 | (0x0f & (s >> 8));
		res[7] = s;
		return res
	};
})();