Cross-domain communication for Firefox Add-ons

[sroth]

Initiate an XMLHttpRequest from a Firefox extension

If trying to get/send information with an extension through an XMLHttpRequest, odds are you will need to go cross domain. Normally this might be an issue, but as long as you execute the request from a chrome window, you will be inside the security scope, and it will be allowed.

Make sure that you are initializing the cross domain XMLHttpRequest from JavaScript? code that is referencing a XUL window. If you try and execute the request in relation to the browser content document, as opposed to the "document" of the XUL window, you will receive a Permission Denied error.