a small simple uuid function for javascript

uuid.es6

let Uuid = () => {
    let r = (s) => {
        let p = (Math.random().toString(16)+"000000000").substr(2,8);
        return s ? "-" + p.substr(0,4) + "-" + p.substr(4,4) : p;
    };
    return r() + r(1) + r(1) + r();
};