javascript判断IFRAME是否加载完成

<iframe id=load1 src="http://leilei.cnblogs.com" onLoad="ionload()" onreadystatechange="ionload()" frameborder=1></iframe>
<script language="javascript">
function iload()
{
    alert(document.getElementById("load1").readyState=='complete');
}

</script>

可惜只能ie玩