offset函数 代码：【复制】 
function offset(e){ 
var t = e.offsetTop; 
var l = e.offsetLeft; 
var w = e.offsetWidth; 
var h = e.offsetHeight - 2; 
while(e = e.offsetParent){ 
t += e.offsetTop; 
l += e.offsetLeft; 
} 
return { 
top : t, 
left : l, 
width : w, 
height : h 
} 
}

代码：【复制】 
function AutoSizeDIV(objID){
	var obj = document.getElementById(objID);
	var obj_div = Offset(obj);
	if (obj.scrollHeight < obj.offsetHeight){
		obj.style.height = obj.scrollHeight + 2;
	}
	if (obj_div.height > 200){
		obj.style.height = '200px';
		obj.style.overflowX = 'hidden';
		obj.style.overflowY = 'auto';
	}
}