<html>
<head>
<script>
function changeSize()
{
document.getElementById("myframe").height="300";
document.getElementById("myframe").width="300";
}
</script>
</head>
<body>
<iframe id="myframe" src="http://ziqiangxuetang.com" height="200" width="200">
<p>Your browser does not support iframes.</p>
</iframe>
<br><br>
<input type="button" onclick="changeSize()" value="Change size">
</body>
</html>