Change:
<del> /* * Copyright (c) Microsoft Open Technologies, Inc.  All rights reserved. * Microsoft Open Technologies would like to thank its contributors, a list * of whom are at http://rx.codeplex.com/wikipage?title=Contributors. * * Licensed under the Apache License, Version 2.0 (the "License"); you * may not use this file except in compliance with the License. You may * obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or * implied. See the License for the specific language governing permissions * and limitations under the License. */ import debugFactory from 'debug'; import { noop, Observable, throwError } from 'rxjs'; import { map } from 'rxjs/operators'; import { isGoodXHRStatus } from './'; const debug = debugFactory('fcc:ajax$'); const root = typeof window !== 'undefined' ? window : {}; // Gets the proper XMLHttpRequest for support for older IE function getXMLHttpRequest() { if (root.XMLHttpRequest) { return new root.XMLHttpRequest(); } else { var progId; try { var progIds = [ 'Msxml2.XMLHTTP', 'Microsoft.XMLHTTP', 'Msxml2.XMLHTTP.4.0' ]; for (var i = 0; i < 3; i++) { try { progId = progIds[i]; if (new root.ActiveXObject(progId)) { break; } } catch (e) { // purposely do nothing noop.noop(e); } } return new root.ActiveXObject(progId); } catch (e) { throw new Error('XMLHttpRequest is not supported by your browser'); } } } // Get CORS support even for older IE function getCORSRequest() { var xhr = new root.XMLHttpRequest(); if ('withCredentials' in xhr) { return xhr; } else if (root.XDomainRequest) { return new root.XDomainRequest(); } else { throw new Error('CORS is not supported by your browser'); } } function parseXhrResponse(responseType, xhr) { switch (responseType) { case 'json': { if (isGoodXHRStatus(xhr.status)) { if ('response' in xhr) { return xhr.responseType ? xhr.response : JSON.parse(xhr.response || xhr.responseText || 'null'); } else { return JSON.parse(xhr.responseText || 'null'); } } else { return null; } } case 'xml': return xhr.responseXML; case 'text': default: return 'response' in xhr ? xhr.response : xhr.responseText; } } function normalizeAjaxSuccessEvent(e, xhr, settings) { return { response: parseXhrResponse(settings.responseType || xhr.responseType, xhr), status: xhr.status, responseType: xhr.responseType, xhr: xhr, originalEvent: e }; } function createNormalizeAjaxErrorEvent(options) { let _body = {}; let _endpoint = ''; if (typeof options === 'string') { _endpoint = options; } else { _body = options.body; _endpoint = options.url; } return (e, xhr, type) => ({ _body, _endpoint, type: type, status: xhr.status, xhr: xhr, originalEvent: e }); } /* * Creates an observable for an Ajax request with either a settings object * with url, headers, etc or a string for a URL. * * @example *   source = Rx.DOM.ajax('/products'); *   source = Rx.DOM.ajax( url: 'products', method: 'GET' }); * * interface Options { *   url: String, // URL of the request *   body?: Object, // The body of the request *   method? = 'GET' : 'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE', *   async? = true: Boolean, // Whether the request is async *   headers?: Object, // optional headers *   crossDomain?: true // if a cross domain request, else false * } * * ajax$(url?: String, options: Options) => Observable[XMLHttpRequest] */ export function ajax$(options) { var settings = { method: 'GET', crossDomain: false, async: true, headers: {}, responseType: 'text', createXHR: function() { return this.crossDomain ? getCORSRequest() : getXMLHttpRequest(); }, normalizeError: createNormalizeAjaxErrorEvent(options), normalizeSuccess: normalizeAjaxSuccessEvent }; if (typeof options === 'string') { settings.url = options; } else { for (var prop in options) { if (hasOwnProperty.call(options, prop)) { settings[prop] = options[prop]; } } } const { normalizeError, normalizeSuccess } = settings; if (!settings.crossDomain && !settings.headers['X-Requested-With']) { settings.headers['X-Requested-With'] = 'XMLHttpRequest'; } settings.hasContent = typeof settings.body !== 'undefined'; return new Observable.create(function(observer) { var isDone = false; var xhr; const throwWithMeta = err => { err._body = options.body || {}; err._endpoint = options.url; observer.error(err); }; var processResponse = function(xhr, e) { var status = xhr.status === 1223 ? 204 : xhr.status; if ((status >= 200 && status <= 300) || status === 0 || status === '') { try { observer.next(normalizeSuccess(e, xhr, settings)); observer.complete(); } catch (err) { throwWithMeta(err); } } else { observer.error(normalizeError(e, xhr, 'error')); } isDone = true; }; try { xhr = settings.createXHR(); } catch (err) { throwWithMeta(err); } try { if (settings.user) { xhr.open( settings.method, settings.url, settings.async, settings.user, settings.password ); } else { xhr.open(settings.method, settings.url, settings.async); } var headers = settings.headers; for (var header in headers) { if (hasOwnProperty.call(headers, header)) { xhr.setRequestHeader(header, headers[header]); } } if (!xhr.upload || (!('withCredentials' in xhr) && root.XDomainRequest)) { xhr.onload = function(e) { if (settings.progressObserver) { settings.progressObserver.next(e); settings.progressObserver.complete(); } processResponse(xhr, e); }; if (settings.progressObserver) { xhr.onprogress = function(e) { settings.progressObserver.next(e); }; } xhr.onerror = function(e) { if (settings.progressObserver) { settings.progressObserver.error(e); } observer.error(normalizeError(e, xhr, 'error')); isDone = true; }; xhr.onabort = function(e) { if (settings.progressObserver) { settings.progressObserver.error(e); } observer.error(normalizeError(e, xhr, 'abort')); isDone = true; }; } else { xhr.onreadystatechange = function(e) { if (xhr.readyState === 4) { processResponse(xhr, e); } }; } debug('ajax$ sending content', settings.hasContent && settings.body); xhr.send((settings.hasContent && settings.body) || null); } catch (err) { throwWithMeta(err); } return function() { if (!isDone && xhr.readyState !== 4) { xhr.abort(); } }; }); } // Creates an observable sequence from an Ajax POST Request with the body. // post$(url: String, body: Object) => Observable[Any] export function post$(url, body) { try { body = JSON.stringify(body); } catch (e) { return throwError(e); } return ajax$({ url, body, method: 'POST' }); } // postJSON$(url: String, body: Object) => Observable[Object] export function postJSON$(url, body) { try { body = JSON.stringify(body); } catch (e) { return throwError(e); } return ajax$({ url, body, method: 'POST', responseType: 'json', headers: { 'Content-Type': 'application/json', Accept: 'application/json' }, normalizeError: (e, xhr) => parseXhrResponse('json', xhr) }); } // Creates an observable sequence from an Ajax GET Request with the body. // get$(url: String) => Obserable[Any] export function get$(url) { return ajax$({ url: url }); } /** * Creates an observable sequence from JSON from an Ajax request * * @param {String} url The URL to GET * @returns {Observable} The observable sequence which contains the parsed JSON */ // getJSON$(url: String) => Observable[Object]; export function getJSON$(url) { return ajax$({ url: url, responseType: 'json', headers: { 'Content-Type': 'application/json', Accept: 'application/json' }, normalizeError: (e, xhr) => parseXhrResponse('json', xhr) }).pipe(map(({ response }) => response)); } </del>

Discussion:
Steps to reproduce: to your credit card information and hit submit transaction will not go through (won't show up in Stripe) and you'll get a blank page like this: <img width="1427" alt="Supportournonprofit_freeCodeCamp_org" src="https://user-"
reproducible on master
I am aware of this issue, working on it.