Prompting user to save when they leave a page

Question

I need to prompt a user to save their work when they leave a page. I\'ve tried onbeforeunload but I need to show a styled prompt not the usual dialog box. Facebook has manag

Answer 1

to improve on the answers of the others here I developed a great little script.

    $('.measurement_value').change(function() {
        $(window).bind('beforeunload', function(){
            return 'You have unsaved changes, are you sure you want to leave?';
        });

        $('#MeasurementAdminEditForm').submit(function(){
            $(window).unbind('beforeunload');
        });
        $('#CancelButton').click(function(){
            $(window).unbind('beforeunload');
        });
    });

On each of my form elements I give a class of 'measurement_value' and then only load the beforeunload if one of those elements change. Furthermore I unload the beforeunload on submit of my form and on the click of the cancel button.

hope this helps someone else.