This could be easily done with jquery and the onbeforeunload
event. Using the .serialize()
function you could calculate the state of the form on the returned string once when the page loads and then in the onbeforeunload
event. Then compare the two values and if they are different something indeed has changed in the form.
Example:
<%@ Page Language="C#" %>
<!DOCTYPE html>
<html>
<head id="Head1" runat="server">
<title></title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.min.js"></script>
<script type="text/javascript">
var data = '';
$(function () {
data = $('form').serialize();
});
window.onbeforeunload = function () {
if ($('form').serialize() !== data) {
return 'You have unsaved changes. Are you sure you want to navigate away?';
}
};
</script>
</head>
<body>
<form id="Form1" runat="server">
<asp:TextBox ID="FirstName" runat="server" />
<asp:TextBox ID="LastName" runat="server" TextMode="MultiLine" />
<asp:CheckBox ID="Chk" runat="server" />
<asp:HyperLink ID="Link" runat="server" Text="Go to Google" NavigateUrl="http://www.google.com" />
</form>
</body>
</html>
Some other techniques (like the one presented in the duplicate question that was voted to close for your question) involve in subscribing for the .change()
event of the input elements but they are less reliable as the user could for example type abc
in some input field and then delete it and if you used this technique the form would be considered as dirty although no value actually changed.