说明：代码取自网络，css中注释为笔者学习时添加，js中的注释为原文所有！
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>跟随鼠标移动（大图展示）</title> <style> html,body{ overflow:hidden; } body,div,ul,li{ margin:0; padding:0; } #box ul{ width:768px; height:172px; list-style-type:none; margin:10px auto; } #box li{ float:left; width:170px; height:170px; cursor:pointer; display:inline; border:1px solid #ddd;/*灰白色*/ margin:0 10px; } #box li.active{ border:1px solid #a10000;/*朱红*/ } #box li img{ width:170px; height:170px; vertical-align:top; } #big{ position:absolute; width:400px; height:400px; border:2px solid #ddd;/*灰白色*/ display:none;/*默认隐藏*/ } #big div{ position:absolute; top:0; left:0; width:400px; height:400px; opacity:0.5;/*半透明*/ filter:alpha(opacity=50); background:#fff url(img/loading.gif) 50% 50% no-repeat;/*居中，不重复*/ } </style> <script> window.onload = function () { var aLi = document.getElementsByTagName("li"); var oBig = document.getElementById("big"); var oLoading = oBig.getElementsByTagName("div")[0]; var i = 0; for (i = 0; i < aLi.length; i++) { aLi[i].index = i; //鼠标划过, 预加载图片插入容器并显示 aLi[i].onmouseover = function () { var oImg = document.createElement("img"); //图片预加载 var img = new Image(); img.src = oImg.src = aLi[this.index].getElementsByTagName("img")[0].src.replace(".jpg", "_big.jpg"); //插入大图片 oBig.appendChild(oImg); //鼠标移过样式 this.className = "active"; //显示big oBig.style.display = oLoading.style.display = "block"; //判断大图是否加载成功 img.complete ? oLoading.style.display = "none" : (oImg.onload = function () { oLoading.style.display = "none"; }) }; //鼠标移动, 大图容器跟随鼠标移动 aLi[i].onmousemove = function (event) { var event = event || window.event; var iWidth = document.documentElement.offsetWidth - event.clientX; //设置big的top值 oBig.style.top = event.clientY + 20 + "px"; //设置big的left值, 如果右侧显示区域不够, 大图将在鼠标左侧显示. oBig.style.left = (iWidth < oBig.offsetWidth + 10 ? event.clientX - oBig.offsetWidth - 10 : event.clientX + 10) + "px"; }; //鼠标离开, 删除大图并隐藏大图容器 aLi[i].onmouseout = function () { this.className = ""; oBig.style.display = "none"; //移除大图片 oBig.removeChild(oBig.lastChild) } } }; </script> </head> <body> <div id="box"> <ul> <li><img src="img/shirt_1.jpg" /></li> <li><img src="img/shirt_2.jpg" /></li> <li><img src="img/shirt_3.jpg" /></li> <li><img src="img/shirt_4.jpg" /></li> </ul> </div> <div id="big"><div></div></div> </body> </html>