twitch_chat.js

  function onElementInserted(containerSelector, elementSelector, callback) {

      var onMutationsObserved = function(mutations) {
          mutations.forEach(function(mutation) {
              if (mutation.addedNodes.length) {
                  var elements = $(mutation.addedNodes).find(elementSelector);
                  for (var i = 0, len = elements.length; i < len; i++) {
                      callback(elements[i]);
                  }
              }
          });
      };

      var target = $(containerSelector)[0];
      var config = {
          childList: true,
          subtree: true
      };
      var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
      var observer = new MutationObserver(onMutationsObserved);
      observer.observe(target, config);

  }

  var contestants = [];
  onElementInserted('body', '.message', function(element) {
      var message = $(element).text();
      if (message.includes("!taco")) {
          var user = $(element).parent().find('.from').text();
          var entry = {
              message: message,
              user: user
          }
          contestants.push(entry);
      }
  });