Upgrade React from 16.13.1 to 17.0.1

[aduth]

Why: As a developer, I want to...

• Keep in sync with latest version of dependencies
• Avoid the effort of writing import React from 'react'; in order to use JSX

Release notes:

• https://reactjs.org/blog/2020/10/20/react-v17.html
• https://reactjs.org/blog/2020/08/10/react-v17-rc.html#other-breaking-changes

More about automatic JSX transform: https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html

[aduth]

Looks like TypeScript support for the JSX transform is slated for 4.1.0, currently in beta:

https://devblogs.microsoft.com/typescript/announcing-typescript-4-1-beta/#jsx-factories

Updated here, but unsure if we'd want to pin to a beta version, so reverted to draft pull request.

Could either upgrade React independently, or wait for TypeScript 4.1 stable release.

[jmhooper]

If I understand correctly, upgrading React w/o TS will break type checking? If that's the case my vote is keep them in sync and wait for 4.1 stable.

[jmhooper]

Also, just realized this is 14 days old which makes me think that's the decision we made. My b, must have skipped this PR while catching up after being sick.

[aduth]

The TypeScript types are maintained independently, and it's hard to tell from the history whether it's up-to-date with React 17, but since React 17 was quite uneventful in terms of features, it may very well be the case that there were no API changes to account for in the typings.

TypeScript 4.1.0 is only necessary to take advantage of the automatic JSX transform, which was admittedly a big draw of the upgrade to begin with (in addition to trying to get ahead of a few potential incompatibilities from internal changed behaviors).

I'm failing to recall where I'd seen it, but I'd seen a page which advertised a release date of November 16 for TypeScript 4.1.0, so at this point I think we may as well wait.

[aduth]

TypeScript 4.1.0 was released yesterday. Refreshed the pull request and ready for review.

[jmhooper]

LGTM