function show(){this.a = 1;};
var show2 = new show();
show = function (){this.a = 2;};
show.prototype.a = 3;
var show3 = new show();
alert(show2.a);//1
alert(show3.a);//2
delete(show2.a);
delete(show3.a);
alert(show2.a);//u
alert(show3.a);//3
为什么alert(show2.a);这里是udf
------解决方案--------------------
因为被delete(show2.a); 删了a 了