​x
 
<html>
<body>
<iframe src="/example/hdom/frame_a.html" id="frame1" marginheight="50"></iframe>
<br /><br />
​
<script type="text/javascript">
x=document.getElementById("frame1");
document.write("Top and bottom margins of the iframe are: ");
document.write(x.marginHeight);
</script>
​
</body>
</html>
​