function uuidv4() {
var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 36; i++) { s[i] = hexDigits.substr(Math.floor(Math.random() * 16), 1); } s[14] = "4"; s[19] = hexDigits.substr(s[19] & 3 | 8, 1); s[8] = s[13] = s[18] = s[23] = "-"; var uuid = s.join(""); return uuid; }