IE9 onbeforeunload called twice when window.location changed in button event... minimal reproduction
I've been hammering and hammering at this and just can't get anywhere.
I have a cancel button that does a "window.location = '404.htm';" when clicked. The onbeforeunload handler fires twice, but only if the user clicks "Stay on this page" to the first dialog. A normal navigation (page refresh, going to home page) the onbeforeunload handler only fires once.
I've managed to repro the behavior with a minimal amount of HTML and script:
<!DOCTYPE html>
<html>
<head>
<title>Test page</title>
</head>
<body onbeforeunload="return 'Unsaved changes';">
<form name="form1" id="form1">
<input id='cmdCancel' type="button" value="Cancel" onclick="window.location = '404.htm';" />
</form>
<script type="text/javascript">
/*
* Connecting the events via code makes no difference
*
document.forms[0].cmdCancel.onclick =
function () {
alert('Clicked cancel. About to navigate...');
window.location = '404.htm';
};
window.onbeforeunload = function () {
return "Unsaved changes";
};
*/
</script>
</body>
</html>
There are lots of hits for "onbeforeunload called twice" but no minimal reproduction and no actual solutions.
Any suggestions?
Thanks!
Answer
Try this, this worked for me. This solution was originally posted by Amit at http://social.msdn.microsoft.com/Forums/eu/sharepointinfopath/thread/13000cd8-5c50-4260-a0d2-bc404764966d?prof=required
Remember, disabling the onbeforeunload temporarily and enabling it back after a short while is the key.
var checkChangesEnabled = true;
window.onbeforeunload = confirmExit;
function confirmExit()
{
if(checkChangesEnabled)
{
event.returnValue = "You have not saved your document yet.";
disableCheck();
}
}
function disableCheck()
{
checkChangesEnabled = false;
setTimeout("enableCheck()", "100");
}
function enableCheck()
{
checkChangesEnabled = true;
}