js生成uuid

getuuid() {
                var uid = [];
                var hexDigits = "0123456789abcdefghijklmnopqrst"; // 这里可以随意写长度越大，生成的随机字符串越不容易重复
                for (var i = 0; i < 32; i++) {
                    uid[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
                }
                uid[6] = "4";
                uid[15] = hexDigits.substr((uid[15] & 0x3) | 0x8, 1);
                var uuid = uid.join("");
                return uuid;
},