/**
* Base class for objects that dispatches events.
* @class EventTarget
* @constructor
*/
var EventTarget = function () {
};
module.exports = EventTarget;
EventTarget.prototype = {
constructor: EventTarget,
/**
* Add an event listener
* @method addEventListener
* @param {String} type
* @param {Function} listener
* @return {EventTarget} The self object, for chainability.
*/
addEventListener: function ( type, listener ) {
if ( this._listeners === undefined ){ this._listeners = {}; }
var listeners = this._listeners;
if ( listeners[ type ] === undefined ) {
listeners[ type ] = [];
}
if ( listeners[ type ].indexOf( listener ) === - 1 ) {
listeners[ type ].push( listener );
}
return this;
},
/**
* Check if an event listener is added
* @method hasEventListener
* @param {String} type
* @param {Function} listener
* @return {Boolean}
*/
hasEventListener: function ( type, listener ) {
if ( this._listeners === undefined ){ return false; }
var listeners = this._listeners;
if ( listeners[ type ] !== undefined && listeners[ type ].indexOf( listener ) !== - 1 ) {
return true;
}
return false;
},
/**
* Remove an event listener
* @method removeEventListener
* @param {String} type
* @param {Function} listener
* @return {EventTarget} The self object, for chainability.
*/
removeEventListener: function ( type, listener ) {
if ( this._listeners === undefined ){ return this; }
var listeners = this._listeners;
if ( listeners[type] === undefined ){ return this; }
var index = listeners[ type ].indexOf( listener );
if ( index !== - 1 ) {
listeners[ type ].splice( index, 1 );
}
return this;
},
/**
* Emit an event.
* @method dispatchEvent
* @param {Object} event
* @param {String} event.type
* @return {EventTarget} The self object, for chainability.
*/
dispatchEvent: function ( event ) {
if ( this._listeners === undefined ){ return this; }
var listeners = this._listeners;
var listenerArray = listeners[ event.type ];
if ( listenerArray !== undefined ) {
event.target = this;
for ( var i = 0, l = listenerArray.length; i < l; i ++ ) {
listenerArray[ i ].call( this, event );
}
}
return this;
}
};