1  'use strict';
 2  
 3  if (typeof Promise === 'undefined') {
 4    // Rejection tracking prevents a common issue where React gets into an
 5    // inconsistent state due to an error, but it gets swallowed by a Promise,
 6    // and the user has no idea what causes React's erratic future behavior.
 7    require('promise/lib/rejection-tracking').enable();
 8    window.Promise = require('promise/lib/es6-extensions.js');
 9  }
10  
11  // fetch() polyfill for making API calls.
12  require('whatwg-fetch');
13  
14  // Object.assign() is commonly used with React.
15  // It will use the native implementation if it's present and isn't buggy.
16  Object.assign = require('object-assign');
17  
18  // In tests, polyfill requestAnimationFrame since jsdom doesn't provide it yet.
19  // We don't polyfill it in the browser--this is user's responsibility.
20  if (process.env.NODE_ENV === 'test') {
21    require('raf').polyfill(global);
22  }