Q1578 How can I detect, that the user has closed the window (including the use of alt-F4)?

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Q1578 How can I detect, that the user has closed the window (including the use of alt-F4)?

Netscape Navigator ignores any attempt to catch the window closing. In Internet Explorer 4+ you can use the onBeforeUnload event handler.

The code below will do the trick EXCEPT in Netscape Navigator when the user hits alt-F4 or clicks the [X] in the top right corner (on windows and possibly other platforms):

<html>
<head>
<script language="JavaScript"><!--
function confirmIELeave() {
    event.returnValue = "Before you go, please turn off the light...";
}
function confirmNSLeave(iWindow) {
    if (!document.layers) return;
    if (!iWindow.closed){
        if (!confirm('Are you sure you want to leave this page?'))
            window.location.href = 'javascript:void(0)';
    }
    else window.open(location.href,'newwin');
}
//--></script>
</head>

<body onbeforeunload="confirmIELeave()" onUnload="confirmNSLeave(this)">

<p>Navigate to another page to fire the before unload event. <a href="http://www.netscape.com">go</a>

</body>
</html>

Here is a test to show you how Netscape Navigator fails to detect alt-F4:

<html>
<head>
<title>Testing universalbrowserwrite's authority</title>
<script language="JavaScript1.2"><!--
function doit() {
    if (document.layers) {
         netscape.security.PrivilegeManager.enablePrivilege('UniversalBrowserWrite');
         window.open('noalt.htm','newwin','titlebar=no,width=800,height=600')
    }
}
//--></script>
</head>
<body>
<a href="javascript:doit()">Open without titlebar</a>
</body>

And then in oalt.html:

<script language="JavaScript"><!--
if (document.layers) {
   window.captureEvents(Event.KEYPRESS);
   window.onkeypress=cnclalt;

}
function cnclalt(e) {
alert(e.modifiers);
    if (e.modifiers==1) {
        alert('Please log out');
        return false;
    }
}
//--></script>

Try to press alt here! Nothing! Try alt spacebar - it gives you the system menu. Change the script to e.modifiers==2 and press shift and you get the alert!

Feedback on 'Q1578 How can I detect, that the user has closed the window (including the use of alt-F4)?'

17:37:40 6/21/01 Corvus

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