scripts/node_modules/axios/lib/adapters/xhr.js

import utils from '../utils.js';
import settle from '../core/settle.js';
import transitionalDefaults from '../defaults/transitional.js';
import AxiosError from '../core/AxiosError.js';
import CanceledError from '../cancel/CanceledError.js';
import parseProtocol from '../helpers/parseProtocol.js';
import platform from '../platform/index.js';
import AxiosHeaders from '../core/AxiosHeaders.js';
import { progressEventReducer } from '../helpers/progressEventReducer.js';
import resolveConfig from '../helpers/resolveConfig.js';

const isXHRAdapterSupported = typeof XMLHttpRequest !== 'undefined';

export default isXHRAdapterSupported &&
  function (config) {
    return new Promise(function dispatchXhrRequest(resolve, reject) {
      const _config = resolveConfig(config);
      let requestData = _config.data;
      const requestHeaders = AxiosHeaders.from(_config.headers).normalize();
      let { responseType, onUploadProgress, onDownloadProgress } = _config;
      let onCanceled;
      let uploadThrottled, downloadThrottled;
      let flushUpload, flushDownload;

      function done() {
        flushUpload && flushUpload(); // flush events
        flushDownload && flushDownload(); // flush events

        _config.cancelToken && _config.cancelToken.unsubscribe(onCanceled);

        _config.signal && _config.signal.removeEventListener('abort', onCanceled);
      }

      let request = new XMLHttpRequest();

      request.open(_config.method.toUpperCase(), _config.url, true);

      // Set the request timeout in MS
      request.timeout = _config.timeout;

      function onloadend() {
        if (!request) {
          return;
        }
        // Prepare the response
        const responseHeaders = AxiosHeaders.from(
          'getAllResponseHeaders' in request && request.getAllResponseHeaders()
        );
        const responseData =
          !responseType || responseType === 'text' || responseType === 'json'
            ? request.responseText
            : request.response;
        const response = {
          data: responseData,
          status: request.status,
          statusText: request.statusText,
          headers: responseHeaders,
          config,
          request,
        };

        settle(
          function _resolve(value) {
            resolve(value);
            done();
          },
          function _reject(err) {
            reject(err);
            done();
          },
          response
        );

        // Clean up request
        request = null;
      }

      if ('onloadend' in request) {
        // Use onloadend if available
        request.onloadend = onloadend;
      } else {
        // Listen for ready state to emulate onloadend
        request.onreadystatechange = function handleLoad() {
          if (!request || request.readyState !== 4) {
            return;
          }

          // The request errored out and we didn't get a response, this will be
          // handled by onerror instead
          // With one exception: request that using file: protocol, most browsers
          // will return status as 0 even though it's a successful request
          if (
            request.status === 0 &&
            !(request.responseURL && request.responseURL.indexOf('file:') === 0)
          ) {
            return;
          }
          // readystate handler is calling before onerror or ontimeout handlers,
          // so we should call onloadend on the next 'tick'
          setTimeout(onloadend);
        };
      }

      // Handle browser request cancellation (as opposed to a manual cancellation)
      request.onabort = function handleAbort() {
        if (!request) {
          return;
        }

        reject(new AxiosError('Request aborted', AxiosError.ECONNABORTED, config, request));

        // Clean up request
        request = null;
      };

      // Handle low level network errors
      request.onerror = function handleError(event) {
        // Browsers deliver a ProgressEvent in XHR onerror
        // (message may be empty; when present, surface it)
        // See https://developer.mozilla.org/docs/Web/API/XMLHttpRequest/error_event
        const msg = event && event.message ? event.message : 'Network Error';
        const err = new AxiosError(msg, AxiosError.ERR_NETWORK, config, request);
        // attach the underlying event for consumers who want details
        err.event = event || null;
        reject(err);
        request = null;
      };

      // Handle timeout
      request.ontimeout = function handleTimeout() {
        let timeoutErrorMessage = _config.timeout
          ? 'timeout of ' + _config.timeout + 'ms exceeded'
          : 'timeout exceeded';
        const transitional = _config.transitional || transitionalDefaults;
        if (_config.timeoutErrorMessage) {
          timeoutErrorMessage = _config.timeoutErrorMessage;
        }
        reject(
          new AxiosError(
            timeoutErrorMessage,
            transitional.clarifyTimeoutError ? AxiosError.ETIMEDOUT : AxiosError.ECONNABORTED,
            config,
            request
          )
        );

        // Clean up request
        request = null;
      };

      // Remove Content-Type if data is undefined
      requestData === undefined && requestHeaders.setContentType(null);

      // Add headers to the request
      if ('setRequestHeader' in request) {
        utils.forEach(requestHeaders.toJSON(), function setRequestHeader(val, key) {
          request.setRequestHeader(key, val);
        });
      }

      // Add withCredentials to request if needed
      if (!utils.isUndefined(_config.withCredentials)) {
        request.withCredentials = !!_config.withCredentials;
      }

      // Add responseType to request if needed
      if (responseType && responseType !== 'json') {
        request.responseType = _config.responseType;
      }

      // Handle progress if needed
      if (onDownloadProgress) {
        [downloadThrottled, flushDownload] = progressEventReducer(onDownloadProgress, true);
        request.addEventListener('progress', downloadThrottled);
      }

      // Not all browsers support upload events
      if (onUploadProgress && request.upload) {
        [uploadThrottled, flushUpload] = progressEventReducer(onUploadProgress);

        request.upload.addEventListener('progress', uploadThrottled);

        request.upload.addEventListener('loadend', flushUpload);
      }

      if (_config.cancelToken || _config.signal) {
        // Handle cancellation
        // eslint-disable-next-line func-names
        onCanceled = (cancel) => {
          if (!request) {
            return;
          }
          reject(!cancel || cancel.type ? new CanceledError(null, config, request) : cancel);
          request.abort();
          request = null;
        };

        _config.cancelToken && _config.cancelToken.subscribe(onCanceled);
        if (_config.signal) {
          _config.signal.aborted
            ? onCanceled()
            : _config.signal.addEventListener('abort', onCanceled);
        }
      }

      const protocol = parseProtocol(_config.url);

      if (protocol && platform.protocols.indexOf(protocol) === -1) {
        reject(
          new AxiosError(
            'Unsupported protocol ' + protocol + ':',
            AxiosError.ERR_BAD_REQUEST,
            config
          )
        );
        return;
      }

      // Send the request
      request.send(requestData || null);
    });
  };