Why are constants not imported?

Question

React

constants.js:

'use strict';

export const Constants =  {
  REST_URL: "https://example.com/"
};

app.js:

'use strict';

import React, { Component } from 'react';
import Constants from './Constants';

export default class App extends React.Component {

  constructor(props) {
    super(props);
    console.warn(Constants)  // undefined
    console.warn(JSON.stringify(Constants));
  }
    ...
}

Answer 1

Because you made a named export, so you need to include:
import { Constants } from './Constants';