fuse-box/modules/events/index.js

Fuse-Box a bundler that does it right

function EventEmitter() {
  this._events = this._events || {};
  this._maxListeners = this._maxListeners || undefined;
}
module.exports = EventEmitter;

// Backwards-compat with node 0.10.x
EventEmitter.EventEmitter = EventEmitter;

EventEmitter.prototype._events = undefined;
EventEmitter.prototype._maxListeners = undefined;

// By default EventEmitters will print a warning if more than 10 listeners are
// added to it. This is a useful default which helps finding memory leaks.
EventEmitter.defaultMaxListeners = 10;

// Obviously not all Emitters should be limited to 10. This function allows
// that to be increased. Set to zero for unlimited.
EventEmitter.prototype.setMaxListeners = function(n) {
  if (!isNumber(n) || n < 0 || isNaN(n)) throw TypeError('n must be a positive number');
  this._maxListeners = n;
  return this;
};

EventEmitter.prototype.emit = function(type) {
  var er, handler, len, args, i, listeners;

  if (!this._events) this._events = {};

  // If there is no 'error' event listener then throw.
  if (type === 'error') {
    if (!this._events.error || (isObject(this._events.error) && !this._events.error.length)) {
      er = arguments[1];
      if (er instanceof Error) {
        throw er; // Unhandled 'error' event
      }
      throw TypeError('Uncaught, unspecified "error" event.');
    }
  }

  handler = this._events[type];

  if (isUndefined(handler)) return false;

  if (isFunction(handler)) {
    switch (arguments.length) {
      // fast cases
      case 1:
        handler.call(this);
        break;
      case 2:
        handler.call(this, arguments[1]);
        break;
      case 3:
        handler.call(this, arguments[1], arguments[2]);
        break;
      // slower
      default:
        args = Array.prototype.slice.call(arguments, 1);
        handler.apply(this, args);
    }
  } else if (isObject(handler)) {
    args = Array.prototype.slice.call(arguments, 1);
    listeners = handler.slice();
    len = listeners.length;
    for (i = 0; i < len; i++) listeners[i].apply(this, args);
  }

  return true;
};

EventEmitter.prototype.addListener = function(type, listener) {
  var m;

  if (!isFunction(listener)) throw TypeError('listener must be a function');

  if (!this._events) this._events = {};

  // To avoid recursion in the case that type === "newListener"! Before
  // adding it to the listeners, first emit "newListener".
  if (this._events.newListener)
    this.emit('newListener', type, isFunction(listener.listener) ? listener.listener : listener);

  if (!this._events[type])
    // Optimize the case of one listener. Don't need the extra array object.
    this._events[type] = listener;
  else if (isObject(this._events[type]))
    // If we've already got an array, just append.
    this._events[type].push(listener);
  // Adding the second element, need to change to array.
  else this._events[type] = [this._events[type], listener];

  // Check for listener leak
  if (isObject(this._events[type]) && !this._events[type].warned) {
    if (!isUndefined(this._maxListeners)) {
      m = this._maxListeners;
    } else {
      m = EventEmitter.defaultMaxListeners;
    }

    if (m && m > 0 && this._events[type].length > m) {
      this._events[type].warned = true;
      console.error(
        '(node) warning: possible EventEmitter memory ' +
          'leak detected. %d listeners added. ' +
          'Use emitter.setMaxListeners() to increase limit.',
        this._events[type].length,
      );
      if (typeof console.trace === 'function') {
        // not supported in IE 10
        console.trace();
      }
    }
  }

  return this;
};

EventEmitter.prototype.on = EventEmitter.prototype.addListener;

EventEmitter.prototype.once = function(type, listener) {
  if (!isFunction(listener)) throw TypeError('listener must be a function');

  var fired = false;

  function g() {
    this.removeListener(type, g);

    if (!fired) {
      fired = true;
      listener.apply(this, arguments);
    }
  }

  g.listener = listener;
  this.on(type, g);

  return this;
};

// emits a 'removeListener' event iff the listener was removed
EventEmitter.prototype.removeListener = function(type, listener) {
  var list, position, length, i;

  if (!isFunction(listener)) throw TypeError('listener must be a function');

  if (!this._events || !this._events[type]) return this;

  list = this._events[type];
  length = list.length;
  position = -1;

  if (list === listener || (isFunction(list.listener) && list.listener === listener)) {
    delete this._events[type];
    if (this._events.removeListener) this.emit('removeListener', type, listener);
  } else if (isObject(list)) {
    for (i = length; i-- > 0; ) {
      if (list[i] === listener || (list[i].listener && list[i].listener === listener)) {
        position = i;
        break;
      }
    }

    if (position < 0) return this;

    if (list.length === 1) {
      list.length = 0;
      delete this._events[type];
    } else {
      list.splice(position, 1);
    }

    if (this._events.removeListener) this.emit('removeListener', type, listener);
  }

  return this;
};

EventEmitter.prototype.removeAllListeners = function(type) {
  var key, listeners;

  if (!this._events) return this;

  // not listening for removeListener, no need to emit
  if (!this._events.removeListener) {
    if (arguments.length === 0) this._events = {};
    else if (this._events[type]) delete this._events[type];
    return this;
  }

  // emit removeListener for all listeners on all events
  if (arguments.length === 0) {
    for (key in this._events) {
      if (key === 'removeListener') continue;
      this.removeAllListeners(key);
    }
    this.removeAllListeners('removeListener');
    this._events = {};
    return this;
  }

  listeners = this._events[type];

  if (isFunction(listeners)) {
    this.removeListener(type, listeners);
  } else if (listeners) {
    // LIFO order
    while (listeners.length) this.removeListener(type, listeners[listeners.length - 1]);
  }
  delete this._events[type];

  return this;
};

EventEmitter.prototype.listeners = function(type) {
  var ret;
  if (!this._events || !this._events[type]) ret = [];
  else if (isFunction(this._events[type])) ret = [this._events[type]];
  else ret = this._events[type].slice();
  return ret;
};

EventEmitter.prototype.listenerCount = function(type) {
  if (this._events) {
    var evlistener = this._events[type];

    if (isFunction(evlistener)) return 1;
    else if (evlistener) return evlistener.length;
  }
  return 0;
};

EventEmitter.listenerCount = function(emitter, type) {
  return emitter.listenerCount(type);
};

function isFunction(arg) {
  return typeof arg === 'function';
}

function isNumber(arg) {
  return typeof arg === 'number';
}

function isObject(arg) {
  return typeof arg === 'object' && arg !== null;
}

function isUndefined(arg) {
  return arg === void 0;
}