Axios interceptor

Api.js

import axios from 'axios';
import configureStore from './Store';

const { store } = configureStore();

const instance = axios.create({
  headers: {
    Accept: 'application/json',
    'Content-Type': 'application/json',
  }
});

instance.interceptors.request.use(
  async config => {
    const token = await store.getState().Auth.accessToken;
    config.metadata = { startTime: new Date() };
    if (token) {
      config.headers.Authorization = `Bearer ${token}`;
    }

    return config;
  },
  error => Promise.reject(error)
);

instance.interceptors.response.use(
  response => {
    let duration = new Date() - response.config.metadata.startTime;
    response.duration = duration;
    let weakInternet = response.config.method == 'get' && response.duration > 1200;
    if (weakInternet) {
      try {
        let contentSize = JSON.stringify(response.data).replace(/[\[\]\,\"]/g, '').length / 1000;
        // if content size divided by duration for api call i.e bytes/miliSecond
        // or say (bytes/1000)/(duration/1000) which is KBps is greater than 50KBps, its not weak
        weakInternet = contentSize / (duration / 1000) < 50;
      } catch (error) {}
    }

    PubSub. publishSync(MESSAGE_TOPICS.LOW_NETWORK, { weakInternet }, 'Success');
    return response;
  },
  error => {
    return Promise.reject(error);
  }
);

export default instance;