兼容各个浏览器的事件监听代码

EventUtil = {
    /*事件添加*/
    addListener: function(target,type,handler){
        if(target.addEventListener){
            target.addEventListener(type,handler);
        }else if(target.attachEvent){
            target.attachEvent(‘on‘+type,function（）{
                handler.call(target)  /*让handler中的this指向目标元素*/
            });
        }else{
            target[‘on‘+type] = handler;
        }
    }，
    /*事件移除*/
    removeListener: function(target,type,handler){
        if(target.removeEventListener){
            target.removeEventListener(type,handler);
        }else if(target.detachEvent){
            target.detachEvent(‘on‘+type,handler);
        }else{
            target[‘on‘+type] = null;
        }
    },
    /*事件对象获取*/
    getEvent: function(e){
        var evt = window.event || e;
        return evt;
    }
    /*获取目标对象*/
    getTarget: function(e){
        var evt = EventUtil.getEvent(e);
        var target;
        if(evt.target){
            target = evt.target;
        }else{
            target = evt.srcElement;
        }
        return target;
    }
    /*停止冒泡*/
    stopPropagation: function(e){
        var evt = EventUtil.getEvent(e);
        if(evt.stopPropagation){
            evt.stopPropagation();
        }else{
            e.cancelBuble = true;
        }
    },
    /*阻止默认行为*/
    preventDefault: function(e){
        var evt = EventUtil.getEvent(e);
        if(evt.preventDefault){
            evt.preventDefault();
        }else{
            evt.returnValue = false;
        }
    }
}