Confirm page exit when there is an Update button on the page.

<script type="text/javascript">
        function getElementsByValue(val, src) {
            var tags;
            var matches = [];
            var i = end = 0;
            if (document.getElementsByTagName) {
                if (!src) {
                    src = document;
                } else if (typeof (src) === 'string') {
                    src = document.getElementById(src);
                }
                tags = src.getElementsByTagName('input');
                for (i, end = tags.length; i < end; i++) {
                    if (tags[i].value && tags[i].value == val) {
                        matches.push(tags[i].id);
                        tags[i] = null;
                    }
                }
            }
            return matches;
        }
        var UpdateButtons = getElementsByValue("Update");
        window.onbeforeunload = function () {
            if (UpdateButtons.length > 0) {
                confirm('You were editing, are you saving changes?')
            }
        }
    </script>