I recently came across this jQuery snippet on Stack Overflow which can be used to convert RSS feeds (which are almost always in XML format) into JSON, which can be used directly in Javascript.

function parseRSS(url, callback) {
    $.ajax({
        url: document.location.protocol + '//ajax.googleapis.com/ajax/services/feed/load?v=1.0&num=10&callback=?&q=' + encodeURIComponent(url),
        dataType: 'json',
        success: function(data) {
        callback(data.responseData.feed);
        }
    });
}

This function calls the RSS feed through Google’s cache, which then returns the feed as JSON (which is much easier to use with Javascript, since it’s just a Javascript object).

Since it’s called through Google, it won’t update immediately (Google needs to crawl the feed for new stories to appear).