js让iframe高度自动

HTML:

<iframe  id="yb_if"   width="940px"   src="连接" frameborder=0 allowfullscreen></iframe>

JS:

//自动同步iframe高度

function reinitIframe(){

    var iframe = document.getElementById("yb_if");

    try{

    iframe.height =  iframe.contentWindow.document.documentElement.scrollHeight;

    }catch (ex){

    }

}

window.setInterval("reinitIframe()", 200);