Function serializeAMimeType

deps/undici/src/lib/web/fetch/data-url.js:472–511

* @see https://mimesniff.spec.whatwg.org/#serialize-a-mime-type

(mimeType)

 * @see https://mimesniff.spec.whatwg.org/#serialize-a-mime-type
 */
function serializeAMimeType (mimeType) {
  assert(mimeType !== 'failure')
  const { parameters, essence } = mimeType

  // 1. Let serialization be the concatenation of mimeType’s
  //    type, U+002F (/), and mimeType’s subtype.
  let serialization = essence

  // 2. For each name → value of mimeType’s parameters:
  for (let [name, value] of parameters.entries()) {
    // 1. Append U+003B (;) to serialization.
    serialization += ';'

    // 2. Append name to serialization.
    serialization += name

    // 3. Append U+003D (=) to serialization.
    serialization += '='

    // 4. If value does not solely contain HTTP token code
    //    points or value is the empty string, then:
    if (!HTTP_TOKEN_CODEPOINTS.test(value)) {
      // 1. Precede each occurrence of U+0022 (") or
      //    U+005C (\) in value with U+005C (\).
      value = value.replace(/[\\"]/ug, '\\$&')

      // 2. Prepend U+0022 (") to value.
      value = '"' + value

      // 3. Append U+0022 (") to value.
      value += '"'
    }

    // 5. Append value to serialization.
    serialization += value
  }

  // 3. Return serialization.
  return serialization
}

/**
 * @see https://fetch.spec.whatwg.org/#http-whitespace