title: Javascript iFrame add to download file in IE7 and IE8
body: <p>I need to download file after ajax request. So I add iframe to a page that posts some data to webmethod and get's file. Here is javascript code what is located at button click handler:</p>
  
  <pre><code>var iframe = $("&lt;iframe id='PDFIframe' style='display:none'&gt;&lt;/iframe&gt;");
  var iForm = $("&lt;form id='PDFForm' action='App/Billing.asmx/GetPDF' target='PDFIframe' method='post' target='_parent'&gt;&lt;/form&gt;")
              .html('&lt;input type="hidden" name="HtmlContent64" value="' + htmlContent64 + '"/&gt;&lt;input type="hidden" name="billNum" value="' + this.billId + '"/&gt;');
  
  iframe.append(iForm);
  tempCmp.append(iframe);
  iForm.submit();
  </code></pre>
  
  <p>But I have an issue at <code>iframe.append(iForm)</code> line at IE 7 and 8. At IE 9 this one works prefect!
  What's wrong in my code?</p>
  
  <p><strong>Edit:</strong> I learn this question more and maybe this issue cause that I test different IE versions in IE9 changing values like at picture. Can mode change cause this issue? Maybe it works ok in real 7 and 8 IE browsers. How do you think?
  <img src="https://i.stack.imgur.com/Jil7r.png" alt="enter image description here"> </p>