Method from

lib/content-type.js:73–79

* Create a ContentType instance from a header value. If the value has been * previously parsed, the cached instance will be returned. * @param {string} headerValue * @returns {ContentType | undefined}

(headerValue)

   * @returns {ContentType | undefined}
   */
  static from (headerValue) {
    let contentType = cache.get(headerValue)
    if (contentType !== undefined) return contentType
    contentType = new ContentType(headerValue)
    cache.set(headerValue, contentType)
    return contentType
  }

  constructor (headerValue) {
    if (headerValue == null || headerValue === '' || headerValue === 'undefined') {