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() {
      // Real errors are hidden from us by the browser
      // onerror should only fire if it's a network error
      reject(new AxiosError('Network Error', AxiosError.ERR_NETWORK, config, request));

      // Clean up request
      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);
  });
}