事件的追加与移除

<script>   var events =[];    window.onload=function(){      for(var i=0;i<events.length;i++){          events[i]();      }    };    var o ={        addEvent:function (fn){            var i=0;            for(;i<events.length;i++){                if(events[i]===fn){                    break;                }            }            if(i !=events.length ){                events.splice(i,1);            }        }

    };    //沙箱    var eventObj =(function(){        var events =[];        window.onload =function(){

        };        return {            addEvent:function(fn){},            removeEvent:function(fn){}        };

    })();

   //添加一个事件处理函数   o.addEvent(function(){       alert(123);   });    var f=function(){        alert(‘可以被移除的函数‘);    };   o.addEvent(f);   o.addEvent(function(){       alert(456);   })   o.removeEvent(f);    alert(‘over‘);