window.onbeforeunload = dialogBox;

function dialogBox()
{
    $("#dialog").html("");
    $("#dialog").append("There appears to be some unsaved changes");
    $( function() {
        $( "#dialog" ).dialog({
            modal: true,
            buttons: {
                Cancel: function() {
                    $(this).dialog( "close" );

                },

                "Save": function() {

                },
            },
        })
    });
}