//css
<style type="text/css">
#enlarge1{position:absolute;100px; height:100px; border:1px solid #000;}
#enlarge2{position:absolute; top:100px; 100px; height:200px ;margin-top:20px; border:1px solid #000; }
#enlarge3{position:absolute; top:10px; left:110px;200px; height:312px; margin-left:10px; margin-top:-2px; border:1px solid #000; }
</style>
//html
<div id="enlarge1"></div>
<div id="enlarge2"></div>
<div id="enlarge3"></div>
//js
<script type="text/javascript">
function enlargeFc(id,x,y){
var option=document.getElementById(id);
var optionWidth=option.clientWidth;
var optionHeight=option.clientHeight;
option.onmouseover=function(){
this.style.width=optionWidth*x+"px";
this.style.height=optionHeight*y+"px";
this.style.background="#0f0";
this.style.zIndex=100000;
}
option.onmouseout=function(){
this.style.width=optionWidth+"px";
this.style.height=optionHeight+"px";
this.style.background="";
this.style.zIndex="auto";
}
}
enlargeFc("enlarge2",1,1);
</script>
//效果