Function parseCacheControlHeader

lib/util/cache.js:124–279

* @see https://www.rfc-editor.org/rfc/rfc9111.html#name-cache-control * @see https://www.iana.org/assignments/http-cache-directives/http-cache-directives.xhtml * @param {string | string[]} header * @returns {import('../../types/cache-interceptor.d.ts').default.CacheControlDirectives}

(header)

 * @returns {import('../../types/cache-interceptor.d.ts').default.CacheControlDirectives}
 */
function parseCacheControlHeader (header) {
  /**
   * @type {import('../../types/cache-interceptor.d.ts').default.CacheControlDirectives}
   */
  const output = {}

  let directives
  if (Array.isArray(header)) {
    directives = []

    for (const directive of header) {
      directives.push(...directive.split(','))
    }
  } else {
    directives = header.split(',')
  }

  for (let i = 0; i < directives.length; i++) {
    const directive = directives[i].toLowerCase()
    const keyValueDelimiter = directive.indexOf('=')

    let key
    let value
    if (keyValueDelimiter !== -1) {
      key = directive.substring(0, keyValueDelimiter).trimStart()
      value = directive.substring(keyValueDelimiter + 1)
    } else {
      key = directive.trim()
    }

    switch (key) {
      case 'min-fresh':
      case 'max-stale':
      case 'max-age':
      case 's-maxage':
      case 'stale-while-revalidate':
      case 'stale-if-error': {
        if (value === undefined || value[0] === ' ') {
          continue
        }

        if (
          value.length >= 2 &&
          value[0] === '"' &&
          value[value.length - 1] === '"'
        ) {
          value = value.substring(1, value.length - 1)
        }

        const parsedValue = parseInt(value, 10)
        // eslint-disable-next-line no-self-compare
        if (parsedValue !== parsedValue) {
          continue
        }

        if (key === 'max-age' && key in output && output[key] >= parsedValue) {
          continue
        }