html5-Common Events-beforeunload events

When we visit certain websites on a daily basis, the following prompt appears when you close the current page:

　　

Beforeunload event can be done, the event occurs: Before the page is unloaded, it can be canceled uninstall and continue to use the original page.

In order to display the above popup dialog box,

You must set event.returnvalue in IE Fiefox as the string to be displayed to the user; also returned as the return value of the function (for Safari and Chrome), the following example

     " Beforeunload ", Function (event) {        event = eventutil.getevent (event);         var " Are you sure you want to leave this page ? " ;         event. returnvalue = message;         return message;    });

IE, Firfox, Safari, Chrome all support beforeunload events. Not supported before OPERA11 version

html5-Common Events-beforeunload events