Alert when browser window closed accidentally

I have a chat application, I want that whenever user accidentally or manually closes the browser ,he should get an alert so that various clean up operations could be carried out. I have more thing i itried to use on before event but I want that to be used for a particular web page as all other web pages are also called on before load. Please help

This is not really a JQuery thing, I use this functions:

function setConfirmUnload(on) {
    window.onbeforeunload = (on) ? unloadMessage : null;
}

function unloadMessage() {
    return "Are you sure you want to leave this page";
}

Then, at any time you can call

setConfirmUnload(true) to enable the confirmation or false if you want to allow them to close the screen without a warning (if you have a close button for instance).

We should prevent or prompt user that on performing these actions he will lose his data.

Click on back browser button.
Click on refresh browser button.
Click on close button of browser.
Click of forward browser button.
Keyboard stroke- Alt+F4 (Close)
Keyboard stroke- F5 (Refresh)
Keyboard stroke-CTRL+ F5 (Refresh)
Keyboard stroke-Shift+ F5 (Refresh)
Change of url
Or anything that cause postback other than your particular submit button.

To explain that I have used two textboxes, one Asp.net submit button with id TestButton. Other postback controls that I have taken are One other asp.net button,one checkbox with autopostback property true,one dropdownlist with autopostback property true. Now I have used all these postback controls so that to show you that we also need to show promt to user about the data lose when user perform actions on these controls. On submit button we will not show the prompt as we have to submit the data with that control action.Here is the sample code.I have set window.onbeforeunload method on controls change.

<html >
<head id="Head1">
    <title></title>

    <script type="text/javascript"
            src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>

    <script type="text/javascript">
        $(function()
        {
            // Prevent accidental navigation away
            $(':input').bind(
                'change', function() { setConfirmUnload(true); });
            $('.noprompt-required').click(
                function() { setConfirmUnload(false); });

            function setConfirmUnload(on)
            {
                window.onbeforeunload = on ? unloadMessage : null;
            }
            function unloadMessage()
            {
                return ('You have entered new data on this page. ' +
                        'If you navigate away from this page without ' +
                        'first saving your data, the changes will be lost.');
            }

            window.onerror = UnspecifiedErrorHandler;
            function UnspecifiedErrorHandler()
            {
                return true;
            }

        }); 

    </script>

</head>
<body>
    <form id="form1" name="myForm" runat="server">
    <div>
        First Name :<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br />
        <br />
        Last Name :<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox><br />
        <br />
        IsMarried :<asp:CheckBox ID="CheckBox1" runat="server" /><br />
        <br />
        <asp:Button runat="server" ID="TestButton" Text="Submit" CssClass="noprompt-required" /><br />
        <br />
        <br />
        <br />
        <br />
        <asp:Button runat="server" ID="AnotherPostbackButton" Text="AnotherPostbackButton"
             /><br />
        <br />
        <asp:CheckBox runat="server" ID="CheckboxWhichCausePostback" Text="CheckboxWhichCausePostback"
            AutoPostBack="true" /><br />
        <br />
        DropdownWhichCausePostback<asp:DropDownList runat="server" ID="DropdownWhichCausePostback"
            AutoPostBack="true">
            <asp:ListItem Text="Text1"></asp:ListItem>
            <asp:ListItem Text="Text2"></asp:ListItem>
        </asp:DropDownList>
        <br />
        <br />
    </div>
    </form>
</body>

Above I have used:

$('.noprompt-required').click(function() { setConfirmUnload(false); });

What I have done in this line is I am calling setConfirmUnload method and passing false as argument which will set the window.onbeforeunload to null. So what that means is on any control where you want that user should not be prompted, give that control the class .noprompt-required and leave other as it is.

You can try the unload event:

$(window).unload( function () { alert("Bye now!"); } );

http://docs.jquery.com/Events/unload

I'm guessing this cleanup is on the client only. It would be interesting to know the nature of these "cleanups".

Alert when browser window closed accidentally

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