Generate a Version 4 UUID

Generates a UUID using the RFC 4122 specification

Version 4 UUIDs take the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is any hex digit and y is in [8, 9, a, b]

Assuming these are generated with sufficient entropy, 1B UUIDs every second for 100 years would be ~50% chance of collision

('' + 1e7 + -1e3 + -4e3 + -8e3 + -1e11)
  .replace(/1|0/g, () => {
    return (0 | Math.random() * 16).toString(16);
  });