Get Content Of Page (including Iframe) From Firefox Plugin

everyone. I'm trying to get data from some page, it's updated using javascript. First, I tried to make java program and periodically get this page from server. But the values on th

Solution 1:

But will I have access to iframe data or it's also forbidden?

Yes, you will have access. Firefox add-ons do not need to respect the normal security policies (depending on what and how they do things, of course).

EDIT (in response to OP comment)

Please see Building an Extension at Mozilla Developer Center for getting started.

You will need to listen to xmlhttprequests as the data in the currency rates table at http://www.fxstreet.com/rates-charts/currency-rates/

You'll probably also want to look at http://www.ashita.org/howto-xhr-listening-by-a-firefox-addon/ for how to listen to the XHR requests.