* {
    margin: 0;
    padding: 0;
  }
img {
    position: absolute;
  }

<img src="../images/cangjingkong.jpg" alt="" id="img"/>

function my$(id) {
        return document.getElementById(id);
    }
 
var evt = {
        getEvent: function (event) {
            return window.event | event;
        },
        getClientX: function (event) {
            return this.getEvent(event).clientX;
        },
        getClientY: function (event) {
            return this.getEvent(event).clientY;
        },
        getScrollLeft: function () {
            return window.pageXOffset || document.body.scrollLeft || document.documentElement.scrollLeft || 0;
        },
        getScrollTop: function () {
            return window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop || 0;
        },
        getPageX: function (event) {
            return this.getEvent(event).pageX ? this.getEvent(event).pageX : this.getClientX(event) + this.getScrollLeft();
        },
        getPageY: function (event) {
            return this.getEvent(event).pageY ? this.getEvent(event).pageY : this.getClientY(event) + this.getScrollTop();
        }
    };
document.onmousemove = function (e) {
            my$("img").style.left=evt.getPageX(e)+"px";
            my$("img").style.top=evt.getPageY(e)+"px";
    }

一段window.event和e的兼容代码，还有page的兼容代码，然后图片飘不起来，谷歌里面console也没有报错，请教各位大神指点一下，哪里出错了？