iframe自适应主窗体高度

<iframe src="" frameborder="0" style="overflow-y: auto; overflow-x:hidden;" width=" 100%;" height="100%" id="point_frame" onload="setIframeHeight(this);"></iframe>

function setIframeHeight(iframe) {
            if (iframe) {
                iframe.height = document.documentElement.clientHeight - 50;
            }
        };