event-emitter-es6/index.js

'use strict';

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var DEFAULT_VALUES = {
    emitDelay: 10,
    strictMode: false
};

/**
 * @typedef {object} EventEmitterListenerFunc
 * @property {boolean} once
 * @property {function} fn
 */

/**
 * @class EventEmitter
 *
 * @private
 * @property {Object.<string, EventEmitterListenerFunc[]>} _listeners
 * @property {string[]} events
 */

var EventEmitter = function () {

    /**
     * @constructor
     * @param {{}}      [opts]
     * @param {number}  [opts.emitDelay = 10] - Number in ms. Specifies whether emit will be sync or async. By default - 10ms. If 0 - fires sync
     * @param {boolean} [opts.strictMode = false] - is true, Emitter throws error on emit error with no listeners
     */

    function EventEmitter() {
        var opts = arguments.length <= 0 || arguments[0] === undefined ? DEFAULT_VALUES : arguments[0];

        _classCallCheck(this, EventEmitter);

        var emitDelay = void 0,
            strictMode = void 0;

        if (opts.hasOwnProperty('emitDelay')) {
            emitDelay = opts.emitDelay;
        } else {
            emitDelay = DEFAULT_VALUES.emitDelay;
        }
        this._emitDelay = emitDelay;

        if (opts.hasOwnProperty('strictMode')) {
            strictMode = opts.strictMode;
        } else {
            strictMode = DEFAULT_VALUES.strictMode;
        }
        this._strictMode = strictMode;

        this._listeners = {};
        this.events = [];
    }

    /**
     * @protected
     * @param {string} type
     * @param {function} listener
     * @param {boolean} [once = false]
     */


    _createClass(EventEmitter, [{
        key: '_addListenner',
        value: function _addListenner(type, listener, once) {
            if (typeof listener !== 'function') {
                throw TypeError('listener must be a function');
            }

            if (this.events.indexOf(type) === -1) {
                this._listeners[type] = [{
                    once: once,
                    fn: listener
                }];
                this.events.push(type);
            } else {
                this._listeners[type].push({
                    once: once,
                    fn: listener
                });
            }
        }

        /**
         * Subscribes on event type specified function
         * @param {string} type
         * @param {function} listener
         */

    }, {
        key: 'on',
        value: function on(type, listener) {
            this._addListenner(type, listener, false);
        }

        /**
         * Subscribes on event type specified function to fire only once
         * @param {string} type
         * @param {function} listener
         */

    }, {
        key: 'once',
        value: function once(type, listener) {
            this._addListenner(type, listener, true);
        }

        /**
         * Removes event with specified type. If specified listenerFunc - deletes only one listener of specified type
         * @param {string} eventType
         * @param {function} [listenerFunc]
         */

    }, {
        key: 'off',
        value: function off(eventType, listenerFunc) {
            var _this = this;

            var typeIndex = this.events.indexOf(eventType);
            var hasType = eventType && typeIndex !== -1;

            if (hasType) {
                if (!listenerFunc) {
                    delete this._listeners[eventType];
                    this.events.splice(typeIndex, 1);
                } else {
                    (function () {
                        var removedEvents = [];
                        var typeListeners = _this._listeners[eventType];

                        typeListeners.forEach(
                        /**
                         * @param {EventEmitterListenerFunc} fn
                         * @param {number} idx
                         */
                        function (fn, idx) {
                            if (fn.fn === listenerFunc) {
                                removedEvents.unshift(idx);
                            }
                        });

                        removedEvents.forEach(function (idx) {
                            typeListeners.splice(idx, 1);
                        });

                        if (!typeListeners.length) {
                            _this.events.splice(typeIndex, 1);
                            delete _this._listeners[eventType];
                        }
                    })();
                }
            }
        }

        /**
         * Applies arguments to specified event type
         * @param {string} eventType
         * @param {*[]} eventArguments
         * @protected
         */

    }, {
        key: '_applyEvents',
        value: function _applyEvents(eventType, eventArguments) {
            var typeListeners = this._listeners[eventType];

            if (!typeListeners || !typeListeners.length) {
                if (this._strictMode) {
                    throw 'No listeners specified for event: ' + eventType;
                } else {
                    return;
                }
            }

            var removableListeners = [];
            typeListeners.forEach(function (eeListener, idx) {
                eeListener.fn.apply(null, eventArguments);
                if (eeListener.once) {
                    removableListeners.unshift(idx);
                }
            });

            removableListeners.forEach(function (idx) {
                typeListeners.splice(idx, 1);
            });
        }

        /**
         * Emits event with specified type and params.
         * @param {string} type
         * @param eventArgs
         */

    }, {
        key: 'emit',
        value: function emit(type) {
            var _this2 = this;

            for (var _len = arguments.length, eventArgs = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
                eventArgs[_key - 1] = arguments[_key];
            }

            if (this._emitDelay) {
                setTimeout(function () {
                    _this2._applyEvents.call(_this2, type, eventArgs);
                }, this._emitDelay);
            } else {
                this._applyEvents(type, eventArgs);
            }
        }

        /**
         * Emits event with specified type and params synchronously.
         * @param {string} type
         * @param eventArgs
         */

    }, {
        key: 'emitSync',
        value: function emitSync(type) {
            for (var _len2 = arguments.length, eventArgs = Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
                eventArgs[_key2 - 1] = arguments[_key2];
            }

            this._applyEvents(type, eventArgs);
        }

        /**
         * Destroys EventEmitter
         */

    }, {
        key: 'destroy',
        value: function destroy() {
            this._listeners = {};
            this.events = [];
        }
    }]);

    return EventEmitter;
}();

module.exports = EventEmitter;