​x
 
<html>
<head>
<script type="text/javascript">
function setHeight()
{
document.getElementById("b1").style.height="50px";
}
</script>
</head>
<body>
​
<input type="button" id="b1" onclick="setHeight()" value="Change height of button to 50 px" />
​
</body>
</html>
​