js控制iframe高度自动撑开

<iframe src="index.html" width="100%" name="" id="myiframe" scrolling="no" onload="changeFrameHeight()" frameborder="0"></iframe>

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

    }