function flattenJSON( jsonKeys, times, values, valuePropertyName ) {

	let i = 1, key = jsonKeys[ 0 ];

	while ( key !== undefined && key[ valuePropertyName ] === undefined ) {

		key = jsonKeys[ i ++ ];

	}

	if ( key === undefined ) return; // no data

	let value = key[ valuePropertyName ];
	if ( value === undefined ) return; // no data

	if ( Array.isArray( value ) ) {

		do {

			value = key[ valuePropertyName ];

			if ( value !== undefined ) {

				times.push( key.time );
				values.push( ...value ); // push all elements

			}

			key = jsonKeys[ i ++ ];

		} while ( key !== undefined );

	} else if ( value.toArray !== undefined ) {

		// ...assume THREE.Math-ish

		do {

			value = key[ valuePropertyName ];

			if ( value !== undefined ) {

				times.push( key.time );
				value.toArray( values, values.length );

			}

			key = jsonKeys[ i ++ ];

		} while ( key !== undefined );

	} else {

		// otherwise push as-is

		do {

			value = key[ valuePropertyName ];

			if ( value !== undefined ) {

				times.push( key.time );
				values.push( value );

			}

			key = jsonKeys[ i ++ ];

		} while ( key !== undefined );

	}

}
Used for parsing AOS keyframe formats.

@param {Array<number>} jsonKeys - A list of JSON keyframes.
@param {Array<number>} times - This array will be filled with keyframe times by this function.
@param {Array<number>} values - This array will be filled with keyframe values by this function.
@param {string} valuePropertyName - The name of the property to use.