dlebedynskyi

// https://medium.com/javascript-inside/safely-accessing-deeply-nested-values-in-javascript-99bf72a0855a
const idx = p => o =>
  p.reduce((xs, x) =>
    (xs && xs[x]) ? xs[x] : null, o)
const getUserComments = idx(['posts', 0, 'comments'])

const user = {}

console.log(getUserComments(user))

dlebedynskyi

window.__testCleanup = () => {
  const unregisterSW = () => {
    return navigator.serviceWorker.getRegistrations()
    .then((registrations) => {
      const unregisterPromise = registrations.map((registration) => {
        return registration.unregister();
      });
      return Promise.all(unregisterPromise);
    });
  };

dlebedynskyi

import React from 'react';
/**
 * Server only Provider component that passes promises as context 
 */
export default class ServerFetchProvider extends React.Component {
  static childContextTypes = {
    serverFetchPromises: React.PropTypes.array
  };

  static propTypes = {