iframe自适应高度

<iframe src="http://www.cncsen.com/news!list.action?code=6" id="itwo" frameborder="0" onscroll="no" onload="changeFrameHeight()" style="width: 100%;"></iframe>

        function changeFrameHeight() {
            var ifm = document.getElementById("itwo");
            ifm.height = document.documentElement.clientHeight - 5;
        }
        window.onresize = function() {
            changeFrameHeight();
        }