observe.js

    /**
     * Observe the DOM for changes to find new Cavy topics.
     */
    var observeDOM = (function() {

        var MutationObserver = window.MutationObserver || window.WebKitMutationObserver,
            eventListenerSupported = window.addEventListener;

        return function(obj, callback) {
            if (MutationObserver) {
                var obs = new MutationObserver(function(mutations, observer) {
                    if (mutations[0].addedNodes.length || mutations[0].removedNodes.length) {
                        callback();
                    }
                });
                obs.observe( obj, {childList: true, subtree: true});
            } else if (eventListenerSupported) {
                obj.addEventListener('DOMNodeInserted', callback, false);
                obj.addEventListener('DOMNodeRemoved', callback, false);
            }
        }

    })();

    observeDOM(document.getElementsByTagName('body')[0], function() {
        parseTopicElements();
    });

where parseTopicElements is a fuction that runs a query selector to find all [data-cavy-topic..