A quick google shows this for FF (taken from a thread in StackOverflow):
> In Firefox you can completely disable beforeunload events by setting dom.disable_beforeunload to true in about:config. Extensions may be needed for other browsers.
A word of caution: I'm not 100% sure, but I wonder if some web collaboration tools might use this to ensure data has been synced with a server.
> In Firefox you can completely disable beforeunload events by setting dom.disable_beforeunload to true in about:config. Extensions may be needed for other browsers.
A word of caution: I'm not 100% sure, but I wonder if some web collaboration tools might use this to ensure data has been synced with a server.