Viewmodels - Building blocks

Viewmodels.js

var Trigger = function () {
  if (!this instanceof Trigger) {
    return new Trigger();
  }
  
  var self = PausableSubscriberExtension(
      DisposableExtension(
        FocusExtension(
          EnableExtension(
            VisibleExtension(
              this))))),
    triggerCallback;

  self.Command = function () {
    triggerCallback();
  };

  self.setCallback = function (callback) {
    triggerCallback = callback;
  };

  return self;
};