JavaScript Capture window Shutdown Event _javascript tips

1. Redefining the Window.onbeforeunload () event with JavaScript
You can define a function in JavaScript.
function Window.onbeforeunload () {Alert ("Close Window")}
The alert () event will be executed before closing the window, and you can also decide whether to close the window
function Window.onbeforeunload () {
if (event.clientx>document.body.clientwidth && event.clienty<0 | | Event.altkey)
Window.event.returnvalue= "Are you sure you want to exit this page? ";
}
2. Using the OnUnload method
Add the OnUnload event to the body tag
Body onunload= "myclose ()"
And then define the Myclose () method in JavaScript.
However, the OnUnload method is performed after the window is closed, not before the window is closed, if you want to make a decision before closing the window, use the first method