gistfile1.js

    var feedData = [];
    feedData.callbacks = [];

       feedData.callbacks.insertNewItems = function(item) {
          // ...
       };

       feedData.callbacks.updateNumberOfImages = function(data) {
          // ...
       };
       
       feedData.callbacks.updateTitle = function(data) {
          // ...
       };

       feedData.callbacks.push(feedData.callbacks.insertNewItems);
       feedData.callbacks.push(feedData.callbacks.updateNumberOfImages);
       feedData.callbacks.push(feedData.callbacks.updateTitle);