Function xhrRequest

src/document-fetcher.js:54–107

* * * @param {string} input * @param {!FetchInitDef} init * @return {!Promise<!{response: !Response, xhr: !XMLHttpRequest}>} * @private

(input, init)

 * @private
 */
function xhrRequest(input, init) {
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open(init.method || 'GET', input, true);
    xhr.withCredentials = init.credentials == 'include';
    xhr.responseType = 'document';
    // Incoming headers are in fetch format,
    // so we need to convert them into xhr.
    for (const header in init.headers) {
      xhr.setRequestHeader(header, init.headers[header]);
    }

    xhr.onreadystatechange = () => {
      if (xhr.readyState < /* STATUS_RECEIVED */ 2) {
        return;
      }
      if (xhr.status < 100 || xhr.status > 599) {
        xhr.onreadystatechange = null;
        reject(user().createExpectedError(`Unknown HTTP status ${xhr.status}`));
        return;
      }
      // TODO(dvoytenko): This is currently simplified: we will wait for the
      // whole document loading to complete. This is fine for the use cases
      // we have now, but may need to be reimplemented later.
      if (xhr.readyState == /* COMPLETE */ 4) {
        const options = {
          status: xhr.status,
          statusText: xhr.statusText,
          headers: parseHeaders(xhr.getAllResponseHeaders()),
        };
        const response = new Response(
          '',
          /** @type {!ResponseInit} */ (options)
        );
        const promise = assertSuccess(response).then((response) => ({
          response,
          xhr,
        }));
        resolve(promise);
      }
    };
    xhr.onerror = () => {
      reject(user().createExpectedError('Request failure'));
    };
    xhr.onabort = () => {
      reject(user().createExpectedError('Request aborted'));
    };
    if (init.method == 'POST') {
      xhr.send(/** @type {!FormData} */ (init.body));
    } else {
      xhr.send();
    }
  });
}

/**
 * Parses XHR's response headers into JSONObject.