I'm using the code that netadictos posted to the question here. All I want to do is to display a warning when a user is navigating away from or closing a window/tab.
The code that netadictos posted seems to work fine in IE7, FF 3.0.5, Safari 3.2.1, and Chrome but it doesn't work in Opera v9.63. Does anyone know of way of doing the same thing in Opera?
Thx, Trev
onbeforeunload is now supported in Opera 15 based on the WebKit engine but not in any prior versions based on Presto.
Opera does not support window.onbeforeunload at the moment. It will be supported in some future version, but has not been a sufficiently high priority to get implemented as of Opera 11.
Mobile Safari (iPhone/iPad) also doesn't support onbeforeunload, and I strongly suspect it is not likely to.
For detecting back/forward navigation there may be workarounds e.g. see Is there an alternative method to use onbeforeunload in mobile safari?.
来源：https://stackoverflow.com/questions/390260/onbeforeunload-in-opera