JavaScript capture window close event

1. Use javascript to redefineWindow. onbeforeunload () event
Define a function in javascript.
Function window. onbeforeunload () {alert ("Close window ")}
The alert () event will be executed before closing the window. 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. Use the onUnload Method
Add an onUnload Event to the body tag
Body onUnload = "myClose ()"
Then define the myClose () method in javascript
However, the onUnload method is executed after the window is closed, instead of before the window is closed. If you want to make a judgment before closing the window, use the first method.