生成UUID

   /*\      * Returns RFC4122, version 4 ID     \*/     var createUUID = (function (uuidRegEx, uuidReplacer) {         return function () {             return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(uuidRegEx, uuidReplacer).toUpperCase();         };     })(/[xy]/g, function (c) {         var r = Math.random() * 16 | 0,             v = c == "x" ? r : (r & 3 | 8);         return v.toString(16);     });