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<a href="#" id="a1">点击</a>

var eventUtil = {
        //添加句柄
        addHandler:function(element,type,handler){
            if(element.addEventListener){
                element.addEventListener(type,handler,false);
            }else if(element.detachEvent){
                element.detachEvent('on'+type,handler);
            }else{
                element['on'+type] = handler;
            }
        },
        //删除句柄
        removeHandler:function(element,type,handler){
            if(element.removeEventListener){
                element.removeEventListener(type,handler,false);
            }else if(element.attachEvent){
                element.attachEvent('on'+type,handler);
            }else{
                element['on'+type] = null;
            }
        }
    };
    (function(){
        var oA = document.getElementById("a1");
        function alert1(){
            alert("1")
        }
        eventUtil.addHandler(oA,"click",alert1);
    })();