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Andrew Clark
c635807875
`use` can avoid suspending on already resolved data by yielding to microtasks. In a real, browser environment, we do this by scheduling a platform task (i.e. postTask). In a test environment, tasks are scheduled on a special internal queue so that they can be flushed by the `act` testing API. So we need to add support for this in `act`. This behavior only works if you `await` the thenable returned by the `act` call. We currently do not require that users do this. So I added a warning, but it only fires if `use` was called. The old Suspense pattern will not trigger a warning. This is to avoid breaking existing tests that use Suspense. The implementation of `act` has gotten extremely complicated because of the subtle changes in behavior over the years, and our commitment to maintaining backwards compatibility. We really should consider being more restrictive in a future major release. The changes are a bit confusing so I did my best to add inline comments explaining how it works. ## Test plan I ran this against Facebook's internal Jest test suite to confirm nothing broke
react
React is a JavaScript library for creating user interfaces.
The react package contains only the functionality necessary to define React components. It is typically used together with a React renderer like react-dom for the web, or react-native for the native environments.
Note: by default, React will be in development mode. The development version includes extra warnings about common mistakes, whereas the production version includes extra performance optimizations and strips all error messages. Don't forget to use the production build when deploying your application.
Usage
import { useState } from 'react';
import { createRoot } from 'react-dom/client';
function Counter() {
const [count, setCount] = useState(0);
return (
<>
<h1>{count}</h1>
<button onClick={() => setCount(count + 1)}>
Increment
</button>
</>
);
}
const root = createRoot(document.getElementById('root'));
root.render(<Counter />);