<html>
<head>
<style type="text/css">
input
{
position:absolute;
}
</style>
<script src="https://cdn.bootcss.com/jquery/1.6.4/jquery.js"></script>
<script type="text/javascript">
function setTopEdgex(){
document.getElementById("b1").style.top="100px";
}
function setTopEdge2()
{
//var ttt=document.getElementsByClassName("xxx");
//ttt.style="150px";
// document.getElementsByClassName("xxx")[0].style.cssText="border:5px solid black;top:150px;"
//document.getElementsByClassName("xxx")[0].style.top="150px";
var k=document.getElementsByTagName("input");
var target;
for(var i=0;i<k.length;i++)
{
if(k[i].getAttribute("abc")=="__abc") target=k[i];
}
//offsetTop 只是可讀的，如果要修改不行。只能用style.top 進行修改。 style.top= value+'px'; 如下：
target.style.top="150px";
}
function myFc() {
var x = document.getElementsByClassName("exp col");
x[0].style.backgroundColor = "red";
}
</script>
</head>
<body>
<input type="button" id="b1" abc="__abc" class="xxx" style="left:20px;top:20px;" onclick="setTopEdgex()" value="Set top edge to 100 px" />
<input type="button" id="b2" style="left:20px;top:40px;" onclick="setTopEdge2()" value="22" />
</body>
</html>