Function extractBody

lib/web/fetch/body.js:39–243

* Extract a body with type from a byte sequence or BodyInit object * * @param {import('../../../types').BodyInit} object - The BodyInit object to extract from * @param {boolean} [keepalive=false] - If true, indicates that the body * @returns {[{stream: ReadableStream, source: any, length: number

(object, keepalive = false)

 * @see https://fetch.spec.whatwg.org/#concept-bodyinit-extract
 */
function extractBody (object, keepalive = false) {
  // 1. Let stream be null.
  let stream = null
  let controller = null

  // 2. If object is a ReadableStream object, then set stream to object.
  if (webidl.is.ReadableStream(object)) {
    stream = object
  } else if (webidl.is.Blob(object)) {
    // 3. Otherwise, if object is a Blob object, set stream to the
    //    result of running object’s get stream.
    stream = object.stream()
  } else {
    // 4. Otherwise, set stream to a new ReadableStream object, and set
    //    up stream with byte reading support.
    stream = new ReadableStream({
      pull () {},
      start (c) {
        controller = c
      },
      cancel () {},
      type: 'bytes'
    })
  }

  // 5. Assert: stream is a ReadableStream object.
  assert(webidl.is.ReadableStream(stream))

  // 6. Let action be null.
  let action = null

  // 7. Let source be null.
  let source = null

  // 8. Let length be null.
  let length = null

  // 9. Let type be null.
  let type = null

  // 10. Switch on object:
  if (typeof object === 'string') {
    // Set source to the UTF-8 encoding of object.
    // Note: setting source to a Uint8Array here breaks some mocking assumptions.
    source = object

    // Set type to `text/plain;charset=UTF-8`.
    type = 'text/plain;charset=UTF-8'
  } else if (webidl.is.URLSearchParams(object)) {
    // URLSearchParams

    // spec says to run application/x-www-form-urlencoded on body.list
    // this is implemented in Node.js as apart of an URLSearchParams instance toString method
    // See: https://github.com/nodejs/node/blob/e46c680bf2b211bbd52cf959ca17ee98c7f657f5/lib/internal/url.js#L490
    // and https://github.com/nodejs/node/blob/e46c680bf2b211bbd52cf959ca17ee98c7f657f5/lib/internal/url.js#L1100

    // Set source to the result of running the application/x-www-form-urlencoded serializer with object’s list.
    source = object.toString()