Function fetch

lib/web/fetch/index.js:159–300

(input, init = undefined)

// https://fetch.spec.whatwg.org/#fetch-method
function fetch (input, init = undefined) {
  webidl.argumentLengthCheck(arguments, 1, 'globalThis.fetch')

  // 1. Let p be a new promise.
  let p = Promise.withResolvers()

  // 2. Let requestObject be the result of invoking the initial value of
  // Request as constructor with input and init as arguments. If this throws
  // an exception, reject p with it and return p.
  let requestObject

  try {
    requestObject = new Request(input, init)
  } catch (e) {
    p.reject(e)
    return p.promise
  }

  // 3. Let request be requestObject’s request.
  const request = getRequestState(requestObject)

  // 4. If requestObject’s signal’s aborted flag is set, then:
  if (requestObject.signal.aborted) {
    // 1. Abort the fetch() call with p, request, null, and
    //    requestObject’s signal’s abort reason.
    abortFetch(p, request, null, requestObject.signal.reason, null)

    // 2. Return p.
    return p.promise
  }

  // 5. Let globalObject be request’s client’s global object.
  const globalObject = request.client.globalObject

  // 6. If globalObject is a ServiceWorkerGlobalScope object, then set
  // request’s service-workers mode to "none".
  if (globalObject?.constructor?.name === 'ServiceWorkerGlobalScope') {
    request.serviceWorkers = 'none'
  }

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

  // 8. Let relevantRealm be this’s relevant Realm.

  // 9. Let locallyAborted be false.
  let locallyAborted = false

  // 10. Let controller be null.
  let controller = null

  // 11. Add the following abort steps to requestObject’s signal:
  const removeAbortListener = addAbortListener(
    requestObject.signal,
    () => {
      // 1. Set locallyAborted to true.
      locallyAborted = true