I'm a front end developer/designer who has been thrust into the position of some backend developing. I'm in a bit of a time crunch and could use some help/direction/input on some code.

I'm working on a photo contest site and I need the votes for an image to cost a credit. The voting and credits are all set up, I just need the voting to check the database to see if the logged in user has credits to vote, if so, then reduce their credits by 1 and complete the vote.

Here is the voting code:
window.addEvent('domready', function() {
	$$('#jwajaxvote-inline-rating a').each(function(el) {
		el.addEvent('click', function(e) {

			e = new Event(e).stop();

			if (jwallpapers_is_user_voting) {
			} else {
				jwallpapers_is_user_voting = true;

			if (jwallpapers_isUserVoteAllowed == false) {
				return false;

			if (jwallpapers_userAlreadyVoted == true) {
				return false;

			var id = this.getAttribute('id');

			var url = eval("jwallpapers_rating_link_" + id);

			var div1 = $('rating_stars_update');
			var div2 = $('jwajaxvote').empty();
			div2.innerHTML = '<img src="' + jwallpapers_joomla_base_url + 'components/' + jwallpapers_option + '/images/ajax_loader/ajax-loader-rating.gif" border="0" align="absmiddle" />';
			var div3 = $('rating_verbose_update');

			new Ajax(url, {
				method : 'get',
				onComplete : function(response, responseXML) {

					jwallpapers_userAlreadyVoted = true;

					var root = responseXML.documentElement;
					var rating_stars_update = root.getElementsByTagName('rating_stars_update').item(0);
					var rating_count_update = root.getElementsByTagName('rating_count_update').item(0);
					var rating_verbose_update = root.getElementsByTagName('rating_verbose_update').item(0);

					var updateRating = rating_stars_update.firstChild.nodeValue;
					var updateCounter = rating_count_update.firstChild.nodeValue;
					var updateVerbose = rating_verbose_update.firstChild.nodeValue;


					jwallpapers_is_user_voting = false;

I should note this is not my code. I've never done any javascript/ajax coding before. My programmer had done this on a previous version of the site, but he quit and then the site went all haywire and I had to reinstall components which erased what he had done.