JS-鼠标跟随块（一个小圆点跟着鼠标跑）

 <!DOCTYPE html>

 <html>

     <head>

         <meta charset="UTF-8">

         <title></title>

         <meta name="author" content="郭菊锋/702004176@qq.com"/>

         <style type="text/css">

             .div {

                 display: none;

                 position: absolute;

                 width: 30px;

                 height: 30px;

                 margin: -15px 0 0 -15px;

                 background: rgba(37, 0, 255, 0.3);

                 -webkit-border-radius: 50%;

                 -moz-border-radius: 50%;

                 border-radius: 50%;

             }

         </style>

     </head>

     <body>

         <div id="div" class="div">

         </div>

     </body>

 </html>

 <script type="text/javascript">

     window.onload = function() {

         var oDiv = document.getElementById("div");

         window.onmousemove = function(ev) {

             var ev = ev || window.event;

             var ofLeft = document.documentElement.offsetLeft || document.body.offsetLeft;

             var ofTop = document.documentElement.offsetTop || document.body.offsetTop;

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             var oTop = ev.clientY + ofTop;

             oDiv.style.display = "block";

             oDiv.style.left = oLeft + "px";

             oDiv.style.top = oTop +　"px";

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     }

 </script>