Polyfill fetch

Summary: Provide server add-on writers with a well-known fetch API

Reviewed By: mweststrate

Differential Revision: D34447630

fbshipit-source-id: 70386940c12f9e53aa97b3530a7edf1d40b5f2e2

desktop/flipper-server-core/src/FlipperServerImpl.tsx

@@ -7,6 +7,7 @@
  * @format
  */
 
+import './utils/fetch-polyfill';
 import EventEmitter from 'events';
 import {ServerController} from './comms/ServerController';
 import {CertificateExchangeMedium} from './utils/CertificateProvider';

desktop/flipper-server-core/src/utils/fetch-polyfill.tsx

@@ -0,0 +1,32 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import nodeFetch, {
+  Headers as HeadersNF,
+  Request as RequestNF,
+  Response as ResponseNF,
+} from 'node-fetch';
+
+declare module globalThis {
+  // eslint-disable-next-line no-var
+  var fetch: typeof nodeFetch;
+  // eslint-disable-next-line no-var
+  var Headers: typeof HeadersNF;
+  // eslint-disable-next-line no-var
+  var Request: typeof RequestNF;
+  // eslint-disable-next-line no-var
+  var Response: typeof ResponseNF;
+}
+
+if (!globalThis.fetch) {
+  globalThis.fetch = nodeFetch;
+  globalThis.Headers = HeadersNF;
+  globalThis.Request = RequestNF;
+  globalThis.Response = ResponseNF;
+}