index.js
function( userId, id ) {

		return this.memory.joinRoom( userId, id )
		.then( function( id ) {

			if( rooms[ id ] === undefined ) {

				rooms[ id ] = room( this.memory, id );	
			}
			
			return promise.resolve( rooms[ id ] );
		}.bind( this ));
	}
function( userId, id ) {

		return this.memory.joinRoom( userId, id )
		.then( function( id ) {

			if( rooms[ id ] === undefined ) {

				rooms[ id ] = room( this.memory, id );	
			}
			
			return promise.resolve( rooms[ id ] );
		}.bind( this ));
	}
function ( userId , id ) { return this . memory . joinRoom ( userId , id ) . then ( function ( id ) { if ( rooms [ id ] === undefined ) { rooms [ id ] = room ( this . memory , id ) ; } return promise . resolve ( rooms [ id ] ) ; } . bind ( this ) ) ; }
Join a room

@param  {String} userId id of the user whose entering a room
@param {String} id id for the room you'd like to enter
@return {Promise} This promise will resolve by sending a room instance if the room does not exist it will fail
Join a room