crm2013 - javascript - stop the save event

first thing i don't speack about the auto-save system and all the code to diseable the save on a form

i was used the : 

 event.returnValue = false; 

to block the save event when i have check a condition.

want to know what is the new way to stop the save event on crm2013 because this code doesn't work.

language : JavaScript

thks