自定义事件模块引擎

define(function () {
    /**
     * Event listener (singleton)
     */
    // TODO: replace usage of the event listener for the EventBus
    var events = {
        'listeners': [],

        /**
         * Find a single listener by its object
         * @param {Object} object
         * @return {Number} index  -1 when not found
         */
        'indexOf': function (object) {
            var listeners = this.listeners;
            for (var i = 0, iMax = this.listeners.length; i < iMax; i++) {
                var listener = listeners[i];
                if (listener && listener.object == object) {
                    return i;
                }
            }
            return -1;
        },

        /**
         * Add an event listener
         * @param {Object} object
         * @param {String} event       The name of an event, for example 'select'
         * @param {function} callback  The callback method, called when the
         *                             event takes place
         */
        'addListener': function (object, event, callback) {
            var index = this.indexOf(object);
            var listener = this.listeners[index];
            if (!listener) {
                listener = {
                    'object': object,
                    'events': {}
                };
                this.listeners.push(listener);
            }

            var callbacks = listener.events[event];
            if (!callbacks) {
                callbacks = [];
                listener.events[event] = callbacks;
            }

            // add the callback if it does not yet exist
            if (callbacks.indexOf(callback) == -1) {
                callbacks.push(callback);
            }
        },

        /**
         * Remove an event listener
         * @param {Object} object
         * @param {String} event       The name of an event, for example 'select'
         * @param {function} callback  The registered callback method
         */
        'removeListener': function (object, event, callback) {
            var index = this.indexOf(object);
            var listener = this.listeners[index];
            if (listener) {
                var callbacks = listener.events[event];
                if (callbacks) {
                    index = callbacks.indexOf(callback);
                    if (index != -1) {
                        callbacks.splice(index, 1);
                    }

                    // remove the array when empty
                    if (callbacks.length == 0) {
                        delete listener.events[event];
                    }
                }

                // count the number of registered events. remove listener when empty
                var count = 0;
                var events = listener.events;
                for (var e in events) {
                    if (events.hasOwnProperty(e)) {
                        count++;
                    }
                }
                if (count == 0) {
                    delete this.listeners[index];
                }
            }
        },

        /**
         * Remove all registered event listeners
         */
        'removeAllListeners': function () {
            this.listeners = [];
        },

        /**
         * Trigger an event. All registered event handlers will be called
         * @param {Object} object
         * @param {String} event
         * @param {Object} properties (optional)
         */
        'trigger': function (object, event, properties) {
            var index = this.indexOf(object);
            var listener = this.listeners[index];
            if (listener) {
                var callbacks = listener.events[event];
                if (callbacks) {
                    for (var i = 0, iMax = callbacks.length; i < iMax; i++) {
                        callbacks[i](properties);
                    }
                }
            }
        }
    };
    return events;
});

以上是来自visjs的自定义事件模块，不知道为什么他们自己放着没用，看了一下非常实用，所以就直接拿过来用就可以。