DIV中iframe高度自适

<iframe id="mainframe" frameborder="0" scrolling="no" width="100%" runat="server"></iframe>
                       <script type="text/javascript">
                           function reinitIframe() {
                               var iframe = document.getElementById("mainframe");
                               try {
                                   if (iframe.contentDocument && iframe.contentWindow.document.documentElement.scrollHeight) {
                                       iframe.height = iframe.contentWindow.document.documentElement.scrollHeight; //设置iframe在火狐下高度

                                   }
                                   else {
                                       var bHeight = iframe.contentWindow.document.body.scrollHeight;
                                       var dHeight = iframe.contentWindow.document.documentElement.scrollHeight;
                                       var height = Math.max(bHeight, dHeight);
                                       iframe.height = height;
                                   }                              
                               } catch (ex) { }
                           }
                           window.setInterval("reinitIframe()", 200);
                          
                    </script>

</div>