Micro EventEmitter-like library for JS, based on https://github.com/jeromeetienne/microevent.js/blob/master/microevent.js#L12-31 but with method names more closely matching node.js EventEmitter

microevent.js

window.MicroEvent = function() {};

MicroEvent.prototype = {
  on: function(event, listener) {
    this._events = this._events || {};
    this._events[event] = this._events[event] || [];
    this._events[event].push(listener);
  },
  removeListener: function(event, listener) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    this._events[event].splice(this._events[event].indexOf(listener), 1);
  },
  emit: function(event /* , args... */) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    for (var i = 0; i < this._events[event].length; i++)
      this._events[event][i].apply(this, Array.prototype.slice.call(arguments, 1));
  }
};

MicroEvent.inherit  = function(destObject) {
  var props = ['on', 'removeListener', 'emit'];
  for (var i = 0; i < props.length; i++) {
    if (typeof destObject === 'function') {
      destObject.prototype[props[i]] = MicroEvent.prototype[props[i]];
    } else {
      destObject[props[i]] = MicroEvent.prototype[props[i]];
    }
  }
};