老师，这是咋回事，帮我看看呗~

<body>
    <button id="btn">点击我</button>
    <script type="text/javascript">
        //兼容所有浏览器
        var EventUtil={
            addHandler:function(element,type,handler){
                if(element.addEventListener){
                    element.addEventListener(type,handler,false);
                }else if(element.attachEvent){
                    element.attachEvent("on"+type,handler);
                }else{
                    element["on"+type]=null;
                }
            },
            removeHandler:function(element,type,handler){
                if(element.removeEventListener){
                    element.removeEventListener(type,handler,false);
                }else if(element.datachEvent){
                    element.datachEvent("on"+type,handler);
                }else{
                    element["on"+type]=null;
                }
            },
            getTarget:function(event){
                return event.getTarget||event.srcElement;
            },
            preventDefault:function(event){
                if(event.preventDefault){
                    event.preventDefault();
                }else{
                    event.returnValue=false;
                }
            },
            stopPropagation:function(event){
                if(event.stopPropagation){
                    event.stopPropagation();
                }else{
                    event.cancelBubble=true;
                }
            },
            getCharCode:function(event){
                if(typeof event.charCode=="number"){
                    return event.charCode;
                }else{
                    return event.keyCode;
                }
            }
        }
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        var btn=document.getElementById("btn");
        EventUtil.addHandler(btn,"touchstart",function(event){
            console.log("当前触摸点的数组是："+event.touches+"(这是一个数组对象)");
            console.log("数组总只包含引起事件的触摸点信息："+event.changeTouches+"(这是一个数组对象)");
            console.log("只包含放在元素上的触摸信息："+event.targerTouches+"(这是一个数组对象)");
        });
    </script>
</body>