js方法重写

<script>
function AB() {
    alert("12");
}

Function.prototype.hookend = function(hook){
        var fn = this;
        return function(){
                ret = fn.apply(this, arguments);
                hook.apply(this, arguments);
                return;
        }
}

AB = AB.hookend(
    function() {
    alert("34");
    }    
)

AB();
</script>
在不动原AB方法的基础下改变AB方法内容！实现了hooker