大家几乎都有在网上购物的经验，有的网站会有一个商品放大镜功能，
就是把鼠标移到图片上的时候，旁边会有另外一张大的图片展示，等同于
放大镜效果，那这样的效果怎样实现的呢，我把代码发给大家，请大家参考。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>放大镜</title> <style> *{margin:0;padding: 0;} #warp{width: 1184px;height:500px;margin:50px auto 0;background-color: #ccc;overflow: hidden;padding: 10px;position: relative;} #warp #minbox{width: 350px;height: 350px;float: left;position: relative;} #maxbox{width: 400px;height: 400px;position: absolute;left: 380px;overflow: hidden;display: none;} #maxbox img{width: 800px;height: 800px;position: absolute;} #con{float: left;margin-left: 20px;} #meng{width: 175px;height: 175px;position: absolute;background-color:yellow;opacity:0.4;filter:alpha(opacity=40);left: 0;top: 0;display: none;} </style> </head> <body> <div id="warp"> <div id="minbox"> <img src="images/min.jpg" alt=""> <p id="meng"></p> </div> <div id="maxbox"> <img src="images/max.jpg" alt=""> </div> <div id="con"> <img src="images/msg.png" alt=""> </div> </div> <script> var minbox=document.getElementById('minbox'); var meng=document.getElementById('meng'); var maxbox=document.getElementById('maxbox'); var maximg=maxbox.getElementsByTagName('img')[0]; var minimg=minbox.getElementsByTagName('img')[0]; function offsetTL(obj){ var ofL=0,ofT=0; while(obj){ ofL+=obj.offsetLeft+obj.clientLeft; ofT+=obj.offsetTop+obj.clientTop; obj=obj.offsetParent; } return{left:ofL,top:ofT}; } minbox.onmousemove=function(e){ var e=e||window.event; meng.style.display='block'; maxbox.style.display='block'; var niubi1=e.clientX-offsetTL(minbox).left-meng.clientWidth/2;//蒙板的X坐标 var niubi2=e.clientY-offsetTL(minbox).top-meng.clientHeight/2;//蒙板的Y坐标 var bili=maximg.clientWidth/minimg.clientWidth; if (niubi1<=0) { niubi1=0; }else if (niubi1>=minbox.clientWidth-meng.clientWidth) { niubi1=minbox.clientWidth-meng.clientWidth; } if (niubi2<=0) { niubi2=0; }else if (niubi2>=minbox.clientHeight-meng.clientHeight) { niubi2=minbox.clientHeight-meng.clientHeight; } console.log(niubi1); console.log(niubi2); meng.style.left=niubi1+'px'; meng.style.top=niubi2+'px'; maximg.style.left=-parseInt(meng.style.left)*bili+'px'; maximg.style.top=-parseInt(meng.style.top)*bili+'px'; } minbox.onmouseout=function(){ meng.style.display='none'; maxbox.style.display='none'; } </script> </body> </html>