Function preferredEncodings

http/_negotiation/encoding.ts:143–164

(
  accept: string,
  provided?: string[],
)

 * negotiated encoding based on the `provided` encodings otherwise just a
 * prioritized array of encodings. */
export function preferredEncodings(
  accept: string,
  provided?: string[],
): string[] {
  const accepts = parseAcceptEncoding(accept);

  if (!provided) {
    return accepts
      .filter(isQuality)
      .sort(compareSpecs)
      .map((spec) => spec.encoding!);
  }

  const priorities = provided.map((type, index) =>
    getEncodingPriority(type, accepts, index)
  );

  return priorities
    .filter(isQuality)
    .sort(compareSpecs)
    .map((priority) => provided[priorities.indexOf(priority)]!);
}