uuidv4 = () => {
    return ([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g, (c) => {
        return (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16);
    });
}
Generate RFC4122-compliant UUIDs.
https://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid?page=1&tab=votes#tab-top
@returns {string} unique uuid string