Angular $eventBus

angular-eventBus.js

// pseudocode

angular.service('$eventBus', function() {
  var listeners = {};
  var mainBus = function(scope) {
    return new ChildBus(mainBus, scope);
  };

  mainBus.emit = function(type) {
    var args = Array.prototype.slice.call(arguments, 1);
    // optimize for calls with 1 or 0 arguments - "apply" is expensive
    forEach(listeners[type], function(listener) {
      if (!args.length) listener();
      else if (!args.length == 1) listener(args[0]);
      else listener.apply(null, args);
    });
  };

  mainBus.on = function(type, listener) {
    // add to listeners
  };

  mainBus.remove = function(type, listener) {
    // remove from listeners
  };

  mainBus.removeAll = function(type) {
    if (type) listeners[type] = [];
    else listeners = {};
  };

  return mainBus;

  function ChildBus(main, scope) {
    var localListeners = {};

    if (scope) // register dispose to removeAll()

    this.on = function(type, listener) {
      main.on(type, listener);
      // add to localListeners
    };

    this.emit = main.emit;

    this.removeListener = function(type, listener) {
      main.removeListener(type, listener);
      // remove from localListeners
    };

    this.removeAll = function(type) {
      // let's do bit more magic to make it linear rather than quadratic...
      // the order of localListeners is the same as in listeners
      // see http://jsperf.com/remove-all-items-from-array
    };
  };
});