<input type=button onclick='a()'>
<script>
function a()
{
l=document.getElementsByTagName("INPUT")
if(l==null) return
for(i=0;i<l.length;i++)
{
if(l[i].type=="button") l[i].className="css2"
}
event.srcElement.className="css1"
}
</script>
<script>
function a()
{
l=document.getElementsByTagName("INPUT")
if(l==null) return
for(i=0;i<l.length;i++)
{
if(l[i].type=="button") l[i].className="css2"
}
event.srcElement.className="css1"
}
</script>
.css1{background: blue}
.css2{background: red}
</style><form name=form1>
<input type=button value=button class=css2 onclick="cc(this)"><br>
<input type=button value=button class=css2 onclick="cc(this)"><br>
<input type=button value=button class=css2 onclick="cc(this)"><br>
<input type=button value=button class=css2 onclick="cc(this)"><br>
</form><script language="JavaScript"><!--
function cc(e)
{
var a = document.form1.elements;
for (var i=0; i<a.length; i++)
if (a[i].type == "button") a[i].className = "css2";
e.className = "css1";
}
//--></script>
.css1{background-color:red}
.css2{background-color:yellow}
<body>
<script>
document.onclick=ch;
function ch(){
var n=document.all.tags("input")
var e=event.srcElement;
for(i=0;i<n.length;i++){
n[i].className="css2"
}
e.className="css1"
}
</script>
<input type=button name=button1 value=button1><input type=button name=button2 value=button1><input type=button name=button3 value=button1>