Popup window address is "about:blank", with text?

I occasionally see popup windows with an address of about:blank, yet the window contains data. If I right-click on that window and select "Properties", I see the URL of the window is NOT about:blank.

Seems like a neat trick.

Can someone please tell me how this is done?

 

hmm, You could make a blank page and <IFRAME> the target page maybe. Haven't tested that though.

 

No, the address bar says "about:blank".

I'd look at the code, but it's happened only on websites after I've done a shopping cart checkout, so I can't go back and look at the HTML without buying something again.

 

Easily done.

1.- They create a popup as about:blank
2.- They write the content using javascript so the page has content but not any url, stay as about:blank to avoid being blocked.

<script language="javascript">
// open the window 
popup = window.open("", "popup", "width=320,height=210,scrollbars=yes"); 

// write to window
popup.document.writeln("<h2>This is written to popup by the main window</h2>"); 
</script>

Code (markup):

 

Thanks, cormack, that's exactly what I'm looking for!

I also found this:
http://www.javascripter.net/faq/writingt.htm