A way to observe url in urlbar of firefox, and get an event every time it changes

Question

I need it for my firefox extension. I don\'t care about waiting the page load completely, I want only observe URL and get an event every time it changes, also when I do history

Answer 1

https://developer.mozilla.org/en/Code_snippets/Progress_Listeners#Example.3a_Notification_when_the_value_in_Address_Bar_changes

Also How can i check if url of current browser tab is changed?