UUID4 (almost) in Javascript, for when you need some more or less unique id.

uuid.js

function S4() {
    return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
}
  
function UUID(short) {
    if (short) {
        return S4() + S4();
    }
    return S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4();
}