Creates a Type 4 UUID using regular expressions.

create_uuid.js

/*
 * Full credit to Byron Salau at http://byronsalau.com/ for this script.
 */
function createUUID() {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
        var r = Math.random() * 16 | 0,
            v = c === 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });
}