determine if element changed inside iframe and create alert on clicking exit element

jquery.tamperframe.js

/*
 * jquery.tamperframe.js
 *  v 0.1
 *
 * Initial Author
 *  John Griffiths
 * 
 * Description
 *  Simpy watches an element for changes, if any encountered flips the flag.
 *  If the exit button is clicked and the flag is true a dialog appears warning user will lose changes.
 * 
 * Params:
 *  watchName   : element (textarea) to watch for changes
 *  exitName    : element (button) which classes as an exit when clicked
 *  messageText : text to show in the alert dialog
 *  watchFrame  : if defined, check for watchName inside iframe of watchFrame
 */

jQuery.tamperFrame = function(watchFrame, watchName, exitName, messageText) {

    // init
    var watchIfr = $(watchFrame);
    var watchEl = watchIfr.eq(0).contents().find(watchName);
	var exitEl = $(exitName);
    messageText = messageText || "Are you sure? \nDoing so will lose any pending changes."; // default text

    // begin
    if (watchEl.length > 0) {

        // store arguments inside elements
        watchEl.data('altered', false);
        exitEl.data('tamper', { frame: watchFrame, watch: watchName, message: messageText});

        // watch any keystrokes, flip flag
        watchEl.keypress(function() {
            $(this).data('altered', true);
        });
        
        // on clicking exit element, if tampered with, throw alert
        exitEl.click(function() {
            var returnVal = true;
            var frame = $(this).data('tamper').frame;
            var watch = $(this).data('tamper').watch;
            var el = $(frame).eq(0).contents().find(watch);
            var flag = $(el).data('altered') || false;

            if (flag) {
                var msg = $(this).data('tamper').message;
                if (confirm(msg) == false) {
                    returnVal = false;
                }
            };
            return returnVal;
        });    
    };
};