I have written a Firefox extension and am currently in the process of updating it for Firefox 4 and adding some new features.

Firefox 4 has a great new notification display that I'd quite like to use and have found plenty of documentation on how to use it. However, for anything less than 4 I have created my own notification window with specific styles.

My question is: how can I detect whether I'm using Firefox 4 or not in the javascript for my extension. Or, is there a better way of doing this?

I have written a Firefox extension and am currently in the process of updating it for Firefox 4 and adding some new features.

Firefox 4 has a great new notification display that I'd quite like to use and have found plenty of documentation on how to use it. However, for anything less than 4 I have created my own notification window with specific styles.

My question is: how can I detect whether I'm using Firefox 4 or not in the javascript for my extension. Or, is there a better way of doing this?

• javascript
• firefox
• firefox-addon
• xul

• 1 If you're referring to PopupNotifications.jsm then you can just look for the window.PopupNotifications variable and if it exists then you can use it otherwise you can use your own notification window. – Neil Commented Feb 11, 2011 at 23:59

2 Answers 2

You can use nsIXULAppInfo:

var appInfo = Components.classes["@mozilla/xre/app-info;1"]
                    .getService(Components.interfaces.nsIXULAppInfo);
// appInfo.version contains the version

You can pare versions with nsIVersionComparator.

Maybe there is a better way, but this definitely works for me.

Following links will give you some idea how to do it.

http://bytes./topic/javascript/answers/822435-how-can-i-get-firefox-version

http://www.quirksmode/js/detect.html