getDependencies( type ) {

    		let dependencies = this.cache.get( type );

    		if ( ! dependencies ) {

    			const parser = this;
    			const defs = this.json[ type + ( type === 'mesh' ? 'es' : 's' ) ] || [];

    			dependencies = Promise.all( defs.map( function ( def, index ) {

    				return parser.getDependency( type, index );

    			} ) );

    			this.cache.add( type, dependencies );

    		}

    		return dependencies;

    	}
Requests all dependencies of the specified type asynchronously, with caching.
@param {string} type
@return {Promise<Array<Object>>}