hello BalajiPolisetty7, it is the intended behaviour that alert() isn't allowed in onbeforeunload. many rogue sites use that to trap and scam users when they want to leave a page...

Thanks for your timely reply . i need to call few java script functions on close of browser tab / window just want to know what is the in built javascript/ jquery functions that i need to use because older version of firefox used to support the window.onbeforeunload so last statement of the event we placed alert so everything got executed and alert box will come . Now with the current version without executing all the statements in the event browser is getting closed.

Please do the needful thanks alot