Drop Jest polyfill for requestAnimationFrame

[kentcdodds]

Sorry, the template didn't really apply here.

I just noticed that in master, react-scripts depends on jest@22.1.2. As of jest@22.0.0, jest-environment-jsdom upgraded to jsdom@11.4 which includes built-in support for requestAnimationFrame.

I'm fairly confident that all that needs to happen here is to simply remove these lines:

create-react-app/packages/react-scripts/config/polyfills.js

Lines 26 to 30 in 75f3fcc

	// In tests, polyfill requestAnimationFrame since jsdom doesn't provide it yet.
	// We don't polyfill it in the browser--this is user's responsibility.
	if (process.env.NODE_ENV === 'test') {
	require('raf').polyfill(global);
	}

Oh, and remove the dependency:

create-react-app/packages/react-scripts/package.json

Line 57 in 75f3fcc

"raf": "3.4.0",

Oh, and while we're at it, if create-react-app is supporting node@>=6 then we can probably get rid of the Object.assign polyfill (and the object-assign dep) as well as the Promise polyfill (and the promise dep).

That should leave the file pretty bare. Something like this I think:

// @remove-on-eject-begin
/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
// @remove-on-eject-end
'use strict';

// fetch() polyfill for making API calls.
require('whatwg-fetch');

[Timer]

I believe you meant next 🤔. But thanks for pointing this out!

As for the polyfills, react-scripts@x will still support IE11 by default so I think it makes sense to keep the Object.assign and Promise polyfills.

[kentcdodds]

Right but this is in the testing environment which will be node 6 or greater as indicated by the engines config in the package.json I linked to 😉

[Timer]

polyfills.js is required in the web builds and by the test environment.

create-react-app/packages/react-scripts/config/webpack.config.prod.js

Line 83 in 75f3fcc

entry: [require.resolve('./polyfills'), paths.appIndexJs],

[kentcdodds]

Ah, that makes sense. Whelp, in that case we could either:

1. Just over-polyfill in the tests (NBD)
2. Separate out polyfills in tests and browser 🤷‍♂️

I don't really care either way personally :)

[andriijas]

Personally Id like the polyfills moved to user land. I know it comes with learning curve but now that we have browserlist targeting in next I think it makes sense to use a service like polyfill.io and improve docs on how users can tweak polyfilling. Which polyfills to use depending on the environments they are targeting etc.

[Timer]

Resolved for next beta