Iframe 自动适应页面的高度

function SetCwinHeight(obj) {    var cwin = obj;    if (document.getElementById) {        if (cwin && !window.opera) {            if (cwin.contentDocument && cwin.contentDocument.body.offsetHeight)                cwin.height = cwin.contentDocument.body.offsetHeight + 30;            else if (cwin.Document && cwin.Document.body.scrollHeight)                cwin.height = cwin.Document.body.scrollHeight + 30;        }    }}

 <iframe id="IframeId_help" scrolling="no" onload="Javascript:SetCwinHeight(this)"                        width="670px" style="border: 0px" frameborder="0"></iframe>