jsdoc/modules/common/events.js

/**
	@module common/events
	@author Michael Mathews <micmath@gmail.com>
	@license Apache License 2.0 - See file 'LICENSE.md' in this project.
 */
(function() { 
    /**
        @mixin module:common/events
    */
    module.exports = {
        /**
            @function module:common/events.on
            @param {string} type
            @param {function} handler
            @returns this
        */
        on: function(type, handler, context) {
            if ( !type ||  !handler ) {
                return;
            }
            if ( !context ) { context = this; }
            
            if ( !this.__bindings ) { this.__bindings = {}; }
            // TODO check here for hasOwnProperty?
            if ( !this.__bindings[type] ) { this.__bindings[type] = []; }
            
            var call = function(e) {
                return handler.call(context, e);
            };
            this.__bindings[type].push( {handler: handler, call: call} );
            
            return this; // chainable
        },
        
        /**
            @function module:common/events.fire
            @param {string} type
            @param {object} [eventData]
            @returns this
        */
        fire: function(eventType, eventData) {
            if ( !eventType || !this.__bindings || !this.__bindings[eventType] ) {
                return;
            }
            
            // run handlers in first-in-first-run order
            for (var i = 0, leni = this.__bindings[eventType].length; i < leni; i++) {
                if ( false === this.__bindings[eventType][i].call(eventData) ) {
                    if (eventData) { eventData.defaultPrevented = true; }
                }
            }
            
            return this; // chainable
        },
        
        /**
            @function module:common/events.removeListener
            @param {string} type
            @param {function} handler
        */
        removeListener: function(type, handler) {
            if ( !type ||  !handler || !this.__bindings || !this.__bindings[type] ) {
                return;
            }
            
            var i = this.__bindings[type].length;
            while ( i-- ) {
                if ( this.__bindings[type][i].handler === handler ) {
                    this.__bindings[type].splice(i, 1);
                }
            }
            
            if (this.__bindings[type].length === 0) {
                delete this.__bindings[type];
            }
        }
    };
})();