<META http-equiv=Content-Type content="text/html; charset=gb2312">
<style>
.a{border: 1px #E7EFF7 solid;}
.b{border: 1px red solid;}
</style>
<script>
var clickId;
function ChangClass(id)
{
if(document.getElementById(clickId) != null )
document.getElementById(clickId).className = "a";
document.getElementById(id).className = "b";
clickId = id;
}
window.onload = function(ev)
{
var box = document.getElementById("form1");
box.onclick = function(ev)
{
ev = ev || window.event;
var element = ev.target || ev.srcElement;
if(element.tagName == "INPUT");
ChangClass(element.id);
}
}
</script>
<form id="form1" name="form1" method="post" action="" >
<label>
<input type="text" name="textfield" class="a" id="I1">
</label>
1
<p>
<input type="text" name="textfield" class="a" id="I2" />
2</p>
<p>
<input type="text" name="textfield" class="a" id="I3" />
3</p>
<p>
<input type="text" name="textfield" class="a" id="I4" />
4
</p>
</form>