This is an example of Fetch function in react-native that contains lots of parameters like: navigation, URL, method, urlParams, headers, base-URL, auth, etraURL, body and connection check

ReactNativeFetch.tsx

import NetInfo from '@react-native-community/netinfo';
import {NavigationProp, ParamListBase} from '@react-navigation/native';

interface FetchProps {
  navigation: NavigationProp<ParamListBase>;
  base?: string;
  url: string;
  method?: 'POST' | 'GET' | 'PUT' | 'PATCH' | 'UPDATE' | 'DELETE';
  body?: any;
  headers?: {
    'Content-Type': 'multipart/form-data' | 'application/json';
    Authorization?: `Bearer ${string}`;
    Accept?: 'application/json';
  };
  urlParams?: any;
  auth?: string;
  extraUrl?: string;
}

interface FetchOptionProp {
  method: 'POST' | 'GET' | 'PUT' | 'PATCH' | 'UPDATE' | 'DELETE';
  headers?: {
    'Content-Type': 'multipart/form-data' | 'application/json';
    Authorization?: string;
    Accept?: 'application/json';
  };
  body?: any;
}

const Fetch = async ({
  navigation,
  url,
  method = 'GET',
  body,
  urlParams,
  headers,
  base = 'http://baseurl.example',
  auth,
  extraUrl,
}: FetchProps) => {
  const options: FetchOptionProp = {
    method: method,
    headers: headers || {
      'Content-Type': 'application/json',
      Accept: 'application/json',
    },
  };
  if (body) {
    options.body = JSON.stringify(body);
  }
  if (auth) {
    options.headers!.Authorization = 'Bearer ' + auth;
  }
  if (urlParams) {
    url = url + `/${urlParams}`;
  }
  if (extraUrl) {
    url = url + extraUrl;
  }
  const completeURL = base + url;
  const state: any = await NetInfo.fetch();
  if (state.isConnected) {
    try {
      const response: any = await fetch(completeURL, options);
      if (response.status !== 200) {
        console.info('status:', response.status);
        console.info('url: ', completeURL);
        console.info('error:', response);
      } else {
        return await response.json();
      }
    } catch (error) {
      console.info(error);
    }
  } else {
    console.log('no internet');
    navigation.navigate('Offline');
  }
};
export default Fetch;