All likes are URLs or pages.
When a page is liked, a username is connected to that page to indicate that the
page is liked by them.
At the same time, other database updates are performed relating to that page.
The old PHP class method of liking a page has been replaced with a new ajax method, using etAjaxLoad() in biscuits.js
onclick the js function likePage(href) is called to record the like using ajax. The JS function uses the jsdata in the markup of the page: