var Observer = function () {

};

Observer.prototype = {
  constructor: Observer,
  subscribe: function (eventName, func) {
    if (!this[eventName]) this[eventName] = [];
    this[eventName].push(func);
  },
  publish: function (eventName, data) {
    var _this = this;
    if (!this[eventName]) this[eventName] = [];
    this[eventName].forEach(function (func) {
      func.call(_this, data);
    });
  }
};