window.onload=function(){

var aLi=document.getElementsByTagName('li');

for(var i=0;i<aLi.length;i++){

aLi[i].timer=null;

aLi[i].onmouseover=function(){

startMove(this,400);

}

aLi[i].onmouseout=function(){

startMove(this,200);

}

}

}

function getStyle(obj,attr)

{

if(obj.currentStyle){return obj.currentStyle[attr];}//IE

else{return getComputedStyle(obj,false)[attr];}//firefox

}

function startMove(obj,iTarget){

var icur=parseInt(getStyle(obj,'height'))

clearInterval(obj.timer);

obj.timer=setInterval(function(){

var speed=(iTarget-icur);

speed=speed>0?Math.ceil(speed):Math.floor(speed);

if(icur==iTarget){clearInterval(obj.timer);}

else{obj.style.height= icur + speed +'px';}

},30);

}

怎么啦，哪里出错了啊，感觉用style就不出效果，offset可以