Use in the beforeunload event listener event.returnValue = "custom message" to define the custom message. Or use event.preventDefault(); to display default message.
- dom
- event
- beforeunload
- ✅ IE 9
- ❎ Firefox 4
- ❎ Opera 37
- ✅ Opera 38
- ❎ Chrome 50
- ✅ Chrome 51