Here is a quick example of what a javascript feed might look like (note that there are tons of different javascript feeds out there ranging from complete articles to article summaries to affiliate products and so forth -- some even include options to have colored boxes and so forth around them).
If you view the source code, you'll see that there is NO TEXT where the javascript code is below -- this is because the search engines CAN'T read javascript.
To see how JS2html takes care of that, check out this same page with JS2Html in action here.
The below javascript feed I easily customized at the article directory amazines.com, where I selected to have three categories of updated articles. GoArticles has a similar javascript feed as well. The below feed is in javascript, which the search engines can't read. JS2Html would simply convert all of that into html, which the search engines can read, and automatically update it whenever the article directory (or feed) updates. You can customize the look, text, etc. however you want.