simple event emitter.js

'use strict';

var Sister;

/**
* @link https://github.com/gajus/sister for the canonical source repository
* @license https://github.com/gajus/sister/blob/master/LICENSE BSD 3-Clause
*/
Sister = function () {
    var sister = {},
        events = {};

    /**
     * @name handler
     * @function
     * @param {Object} data Event data.
     */

    /**
     * @param {String} name Event name.
     * @param {handler} handler
     * @return {listener}
     */
    sister.on = function (name, handler) {
        var listener = {name: name, handler: handler};
        events[name] = events[name] || [];
        events[name].unshift(listener);
        return listener;
    };

    /**
     * @param {listener}
     */
    sister.off = function (listener) {
        var index = events[listener.name].indexOf(listener);

        if (index !== -1) {
            events[listener.name].splice(index, 1);
        }
    };

    /**
     * @param {String} name Event name.
     * @param {Object} data Event data.
     */
    sister.trigger = function (name, data) {
        var listeners = events[name],
            i;

        if (listeners) {
            i = listeners.length;
            while (i--) {
                listeners[i].handler(data);
            }
        }
    };

    return sister;
};

module.exports = Sister;