@expo/metro-runtime/src/async-require/fetchAsync.native.ts

Tools for making advanced Metro bundler features work

/**
 * Copyright (c) 650 Industries.
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

// @ts-expect-error
import Networking from 'react-native/Libraries/Network/RCTNetworking';

type Subscriber = { remove: () => void };

export function fetchAsync(
  url: string
): Promise<{ body: string; status: number; headers: Record<string, string> }> {
  let id: string | null = null;
  let statusCode: number | null = null;
  let responseText: string | null = null;
  let headers: Record<string, string> = {};
  let dataListener: Subscriber | null = null;
  let completeListener: Subscriber | null = null;
  let responseListener: Subscriber | null = null;
  return new Promise<{ body: string; status: number; headers: Record<string, string> }>(
    (resolve, reject) => {
      const addListener = Networking.addListener.bind(Networking) as (
        event: string,
        callback: (props: [string, any, any]) => any
      ) => Subscriber;
      dataListener = addListener('didReceiveNetworkData', ([requestId, response]) => {
        if (requestId === id) {
          responseText = response;
        }
      });
      responseListener = addListener(
        'didReceiveNetworkResponse',
        ([requestId, status, responseHeaders]) => {
          if (requestId === id) {
            statusCode = status;
            headers = responseHeaders;
          }
        }
      );
      completeListener = addListener('didCompleteNetworkResponse', ([requestId, error]) => {
        if (requestId === id) {
          if (error) {
            reject(error);
          } else {
            resolve({ body: responseText!, status: statusCode!, headers });
          }
        }
      });
      (Networking.sendRequest as any)(
        'GET',
        'asyncRequest',
        url,
        {
          'expo-platform': process.env.EXPO_OS,
        },
        '',
        'text',
        false,
        0,
        (requestId: string) => {
          id = requestId;
        },
        true
      );
    }
  ).finally(() => {
    dataListener?.remove();
    completeListener?.remove();
    responseListener?.remove();
  });
}