gistfile1.txt

// say this is the "button" click that makes the iframe fullscreen
$('button.fullscreen').click(function() {

  // fetch existing iframe
  var $iframe = $('#iframeId');

  // clone iframe to push it into a new content area
  var $iframeInstance = $iframe.clone();

  // add clone to body
  $iframeInstance.appendTo('body');

});