<script>
function test()
{
	var t1 = document.getElementById("test1");
	var t2 = document.getElementById("test2");
	var t3 = document.getElementById("test3");
	alert("t1\nstyle.height="+t1.style.height+"\noffsetHeight="+t1.offsetHeight);
	alert("t2\nstyle.height="+t2.style.height+"\noffsetHeight="+t2.offsetHeight);
	alert("t3\nstyle.height="+t3.style.height+"\noffsetHeight="+t3.offsetHeight);
}
</script>
<style>#test3 {height:50px;}</style>
<div id="test1"> 111 </div>
<div id="test2" style="height:30px"> 222 </div>
<div id="test3"> 333 </div>
<button onclick="test()">test</button>