Mainstream browsers support onbeforeunload events (events triggered before page uninstallation). Most websites now use this function to implement it as follows:
The Code is as follows:
Window. onbeforeunload = function (){
Return "are you sure you want to leave the page? ";
}
There is also a way to write
The Code is as follows:
Window. onbeforeunload = function (event ){
(Event | window. event). returnValue = "are you sure you want to exit ";
}
This method is not supported by chrome and safari, but because of the support of ie and ff, html5 is also added to the standard...
As we all know, the events (such as alert and confirm) will be blocked in the pop-up dialog box of the browser. After further operations, the events will continue to be executed.
This is common practice.
The Code is as follows:
Window. onbeforeunload = function (event ){
Return confirm ("are you sure you want to exit ");
}
Here we will pop up two times, and the content after return will serve as a prompt for whether to leave the page ..
