Adding react is export support

[mrgurdeep]

Adding support so that each function of ReactIs is individually accessible

This solve the issue mentioned in #13250

And then finally provide a feature requested in #13272

What is the issue
Tree shaking not enabled with react-is.

import * as ReactIs from "react-is";
ReactIs.isValidElementType(<div />); // true

Expected behavior
Allow importing individual modules from the package.

import { isValidElementType } from "react-is";
isValidElementType(<div />); // true

[pull-bot]

Details of bundled changes.

Comparing: 2a2ef7e...1655525

react-is

File	Filesize Diff	Gzip Diff	Prev Size	Current Size	Prev Gzip	Current Gzip	ENV
react-is.development.js	+12.6%	+10.1%	4.68 KB	5.28 KB	1.29 KB	1.42 KB	UMD_DEV
react-is.production.min.js	🔺+18.8%	🔺+20.7%	1.89 KB	2.25 KB	789 B	952 B	UMD_PROD
react-is.development.js	+13.1%	+11.2%	4.5 KB	5.09 KB	1.24 KB	1.38 KB	NODE_DEV
react-is.production.min.js	🔺+17.5%	🔺+18.7%	1.84 KB	2.16 KB	722 B	857 B	NODE_PROD
ReactIs-dev.js	+12.9%	+10.8%	4.58 KB	5.17 KB	1.27 KB	1.4 KB	FB_WWW_DEV
ReactIs-prod.js	🔺+24.8%	🔺+17.9%	3.68 KB	4.59 KB	1006 B	1.16 KB	FB_WWW_PROD

Generated by 🚫 dangerJS

[mrgurdeep]

@gaearon as you suggested in reduxjs/react-redux#914 (comment)

[pgarciacamou]

I don't understand why you export it twice, I believe that is what is increasing the size of the build files.

[mrgurdeep]

One to maintain backword compatibility. It might be used and stop working. We could have kept one but older usages will fail.

…

On Mon 30 Jul, 2018, 4:56 AM Pablo Garcia, ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In packages/react-is/index.js <#13284 (comment)>: > @@ -10,3 +10,4 @@ 'use strict'; export * from './src/ReactIs'; +export {default} from './src/ReactIs'; I don't understand why exporting it twice. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#13284 (review)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AD7Nn5BfhlMzyQBt8NK0xEKrCN-HGCokks5uLkSrgaJpZM4Vk50w> .

[gaearon]

Sorry, I don't see how this could help.
If you want tree shaking to work, you need to add an ESM build target in the Rollup settings.