Class ContentType

lib/content-type.js:52–191

* ContentType parses and represents the value of the content-type header. * * @see https://httpwg.org/specs/rfc9110.html#media.type * @see https://httpwg.org/specs/rfc9110.html#parameter

 * @see https://httpwg.org/specs/rfc9110.html#parameter
 */
class ContentType {
  #valid = false
  #empty = true
  #type = ''
  #subtype = ''
  #parameters = new Map()
  #string

  /**
   * The shared cache of ContentType instances. The cache is used to avoid
   * creating multiple instances of ContentType for the same header value.
   * @type {Lru<ContentType>}
   */
  static get cache () { return cache }

  /**
   * 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}
   */
  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') {
      return
    }

    let sepIdx = headerValue.indexOf(';')
    if (sepIdx === -1) {
      // The value is the simplest `type/subtype` variant.
      sepIdx = headerValue.indexOf('/')
      if (sepIdx === -1) {
        // Got a string without the correct `type/subtype` format.
        return
      }

      const type = headerValue.slice(0, sepIdx).trimStart().toLowerCase()
      const subtype = headerValue.slice(sepIdx + 1).trimEnd().toLowerCase()

      if (
        typeNameReg.test(type) === true &&
        subtypeNameReg.test(subtype) === true
      ) {
        this.#valid = true
        this.#empty = false
        this.#type = type
        this.#subtype = subtype
      }

      return
    }