How to use JavaScript to access cross domain iFrame content?

Question

I would like to use this code

window.parent.document.getElementById(\'message\').value  += \"\\r\\n\\r\\n[img]\"+response+\"[/img]\";

It works

Answer 1

Take a look at easyXDM, it's an easy to use library that provides a unified API for several tricks used to enable cross domain messaging, ranging from postMessage to the FIM-trick as a last resort.
This is what is used by major services such as Twitter and Disqus.