Add SuspenseList to react-is

[bvaughn]

Resolves #20868

[sizebot]

Comparing: 4190a34...73c472c

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	122.36 kB	122.36 kB	=	39.41 kB	39.41 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	128.94 kB	128.94 kB	=	41.47 kB	41.47 kB
facebook-www/ReactDOM-prod.classic.js	=	404.67 kB	404.67 kB	=	75.15 kB	75.15 kB
facebook-www/ReactDOM-prod.modern.js	=	393.02 kB	393.02 kB	=	73.24 kB	73.24 kB
facebook-www/ReactDOMForked-prod.classic.js	=	404.68 kB	404.68 kB	=	75.15 kB	75.15 kB
oss-experimental/react-is/cjs/react-is.production.min.js	+4.10%	2.37 kB	2.46 kB	+3.03%	0.92 kB	0.95 kB
facebook-www/ReactIs-prod.modern.js	+3.92%	5.54 kB	5.76 kB	+2.60%	1.39 kB	1.42 kB
oss-experimental/react-is/cjs/react-is.development.js	+3.46%	7.71 kB	7.98 kB	+2.08%	2.12 kB	2.16 kB
oss-experimental/react-is/umd/react-is.production.min.js	+3.41%	2.38 kB	2.46 kB	+2.50%	0.96 kB	0.98 kB
oss-experimental/react-is/umd/react-is.development.js	+3.36%	8.29 kB	8.57 kB	+2.19%	2.19 kB	2.24 kB
facebook-www/ReactIs-dev.modern.js	+2.71%	9.87 kB	10.14 kB	+1.68%	2.68 kB	2.73 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-experimental/react-is/cjs/react-is.production.min.js	+4.10%	2.37 kB	2.46 kB	+3.03%	0.92 kB	0.95 kB
facebook-www/ReactIs-prod.modern.js	+3.92%	5.54 kB	5.76 kB	+2.60%	1.39 kB	1.42 kB
oss-experimental/react-is/cjs/react-is.development.js	+3.46%	7.71 kB	7.98 kB	+2.08%	2.12 kB	2.16 kB
oss-experimental/react-is/umd/react-is.production.min.js	+3.41%	2.38 kB	2.46 kB	+2.50%	0.96 kB	0.98 kB
oss-experimental/react-is/umd/react-is.development.js	+3.36%	8.29 kB	8.57 kB	+2.19%	2.19 kB	2.24 kB
facebook-www/ReactIs-dev.modern.js	+2.71%	9.87 kB	10.14 kB	+1.68%	2.68 kB	2.73 kB

Generated by 🚫 dangerJS against 73c472c

[eps1lon]

react has different entrypoints (index.experimental and index.stable) which probably makes more sense to use here as well since then the stable OSS builds won't list these experimental features at all.

[bvaughn]

Not sure I understand.

Those entry points (forks) are what's used by our Rollup build script to generate different NPM bundles, but we don't reference them in tests. We use @gate pragma to enable/disable tests.

Hm. Not sure how to get it working right in this case. I thought I had it but...

[eps1lon]

The idea was that you don't branch inside of isSuspenseList and SuspenseList = ... but instead have index.js exporting everything from ReactIS, index.experimental exporting everything as well, and index.stable (assuming this is the OSS build) exporting everything but the SuspenseList related stuff.

patch

diff --git a/packages/react-is/index.experimental.js b/packages/react-is/index.experimental.js
new file mode 100644
index 000000000..e9934e91f
--- /dev/null
+++ b/packages/react-is/index.experimental.js
@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+'use strict';
+
+export {
+  isAsyncMode,
+  isConcurrentMode,
+  ContextConsumer,
+  isContextConsumer,
+  ContextProvider,
+  isContextProvider,
+  Element,
+  isElement,
+  ForwardRef,
+  isForwardRef,
+  Fragment,
+  isFragment,
+  Lazy,
+  isLazy,
+  Memo,
+  isMemo,
+  Portal,
+  isPortal,
+  Profiler,
+  isProfiler,
+  StrictMode,
+  isStrictMode,
+  Suspense,
+  isSuspense,
+  isValidElementType,
+  // exposeConcurrentModeAPIs
+  SuspenseList,
+  isSuspenseList,
+} from './src/ReactIs';
diff --git a/packages/react-is/index.stable.js b/packages/react-is/index.stable.js
new file mode 100644
index 000000000..efaed673c
--- /dev/null
+++ b/packages/react-is/index.stable.js
@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+'use strict';
+
+export {
+  isAsyncMode,
+  isConcurrentMode,
+  ContextConsumer,
+  isContextConsumer,
+  ContextProvider,
+  isContextProvider,
+  Element,
+  isElement,
+  ForwardRef,
+  isForwardRef,
+  Fragment,
+  isFragment,
+  Lazy,
+  isLazy,
+  Memo,
+  isMemo,
+  Portal,
+  isPortal,
+  Profiler,
+  isProfiler,
+  StrictMode,
+  isStrictMode,
+  Suspense,
+  isSuspense,
+  isValidElementType,
+} from './src/ReactIs';
diff --git a/packages/react-is/src/ReactIs.js b/packages/react-is/src/ReactIs.js
index 9aa1aa23d..dd81ec036 100644
--- a/packages/react-is/src/ReactIs.js
+++ b/packages/react-is/src/ReactIs.js
@@ -72,9 +72,7 @@ export const Portal = REACT_PORTAL_TYPE;
 export const Profiler = REACT_PROFILER_TYPE;
 export const StrictMode = REACT_STRICT_MODE_TYPE;
 export const Suspense = REACT_SUSPENSE_TYPE;
-export const SuspenseList = __EXPERIMENTAL__
-  ? REACT_SUSPENSE_LIST_TYPE
-  : undefined;
+export const SuspenseList = REACT_SUSPENSE_LIST_TYPE;
 
 export {isValidElementType};
 
@@ -146,9 +144,5 @@ export function isSuspense(object: any) {
   return typeOf(object) === REACT_SUSPENSE_TYPE;
 }
 export function isSuspenseList(object: any) {
-  if (__EXPERIMENTAL__) {
-    return typeOf(object) === REACT_SUSPENSE_LIST_TYPE;
-  } else {
-    return false;
-  }
+  return typeOf(object) === REACT_SUSPENSE_LIST_TYPE;
 }

Can't test it right now since I'm on a windows machine and the failing CI tasks crash with Could not locate module scheduler mapped as: C:\Users\eps1lon\Development\react\build2\oss-experimental\scheduler

[bvaughn]

Ah, sorry. I think I misunderstood your question to be about testing. Sounds like you were just suggesting it may be more appropriate to add a fork for react-is to expose the new methods. Yeah, that seems like a reasonable suggestion too.