随机生成uuid序号

function guid() {
            function S4() {
               return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
            }
            return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
        }
        var _uuid = guid();