The `enableHooks` feature flag used to only control whether the API
was exposed on the React package. But now it also determines if the
dispatcher and implementation are included in the bundle.
We're using hooks in www, so I've switched the feature flag to `true`
in the www build.
(Alternatively, we could have two feature flags: one for the
implementation and dispatcher, and one for exposing the API on the
React package.)
* Avoid double commit by re-rendering immediately and reusing children
To support Suspense outside of concurrent mode, any component that
starts rendering must commit synchronously without being interrupted.
This means normal path, where we unwind the stack and try again from the
nearest Suspense boundary, won't work.
We used to have a special case where we commit the suspended tree in an
incomplete state. Then, in a subsequent commit, we re-render using the
fallback.
The first part — committing an incomplete tree — hasn't changed with
this PR. But I've changed the second part — now we render the fallback
children immediately, within the same commit.
* Add a failing test for remounting fallback in sync mode
* Add failing test for stuck Suspense fallback
* Toggle visibility of Suspense children in mutation phase, not layout
If parent reads visibility of children in a lifecycle, they should have
already updated.
This is required to use lazy.
Test Plan:
* Verified lazy works on a real world use case (shows spinner, shows real content).
* Verified that if I change the primary content's styles to have `display: 'none'` then it never appears (i.e., the code in `unhide` reads the styles successfully)
* Add debug tools package
* Add basic implementation
* Implement inspection of the current state of hooks using the fiber tree
* Support useContext hooks inspection by backtracking from the Fiber
I'm not sure this is safe because the return fibers may not be current
but close enough and it's fast.
We use this to set up the current values of the providers.
* rm copypasta
* Use lastIndexOf
Just in case. I don't know of any scenario where this can happen.
* Support ForwardRef
* Add test for memo and custom hooks
* Support defaultProps resolution
Check for existence of `setTimeout` and `clearTimeout` in the runtime
before using them, to ensure runtimes without them (like .NET ClearScript)
do not crash just by importing `react-dom`.
Mostly to catch this:
```js
useEffect(async () => {
// ...
return cleanup;
});
```
Is this too restrictive? Not sure if you would want to do like
```js
useEffect(() => ref.current.style.color = 'red');
```
which would give a false positive here. We can always relax it to only warn on Promises if people complain.
* Simplify imports in ReactChildFiber
* Import type first in ReactCurrentFiber
* Simplify imports in ReactFiberBeginWork
* Simplify imports in ReactFiberScheduler
* Simplify import in ReactFiberTreeReflection
* Simplify import in ReactFiberUnwindWork
* Remove repeated import
* Fix imports from ReactFiberExpirationTime
* Master imports in ReactFiberBeginWork
Removes the `enableDispatchCallback` feature flag and deletes the
associated code. An earlier version of the Hooks proposal included this
feature but we've since decided to remove it.
* [scheduler] Deadline object -> shouldYield
Instead of using a requestIdleCallback-style deadline object, expose a
method Scheduler.shouldYield that returns true if there's a higher
priority event in the queue.
* Nits
Even though we commit the fiber in an incomplete state, we shouldn't
fire any lifecycles or effects.
We already did this for classes, but now with useEffect, the same is
needed for other types of work, too.
Before the fix, the passive effect in the test is never executed.
We were previously waiting until the next commit phase to run effects. Now, we run them before scheduling work.
Effects scheduled by useEffect should not fire until after the browser
has had a chance to paint. However, they should be fired before any
subsequent mutations.
Also adds useMutationEffect and useLayoutEffect. useMutationEffect fires
during the host update phase. useLayoutEffect fires during the post-
update phase (the same phase as componentDidMount
and componentDidUpdate).
