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Move use to APIs (#6774)
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kassens authored Apr 24, 2024
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17 changes: 17 additions & 0 deletions src/content/reference/react/apis.md
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Expand Up @@ -15,3 +15,20 @@ In addition to [Hooks](/reference/react) and [Components](/reference/react/compo
* [`lazy`](/reference/react/lazy) lets you defer loading a component's code until it's rendered for the first time.
* [`memo`](/reference/react/memo) lets your component skip re-renders with same props. Used with [`useMemo`](/reference/react/useMemo) and [`useCallback`.](/reference/react/useCallback)
* [`startTransition`](/reference/react/startTransition) lets you mark a state update as non-urgent. Similar to [`useTransition`.](/reference/react/useTransition)

---

## Resource APIs {/*resource-apis*/}

*Resources* can be accessed by a component without having them as part of their state. For example, a component can read a message from a Promise or read styling information from a context.

To read a value from a resource, use this API:

* [`use`](/reference/react/use) lets you read the value of a resource like a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).
```js
function MessageComponent({ messagePromise }) {
const message = use(messagePromise);
const theme = use(ThemeContext);
// ...
}
```
18 changes: 0 additions & 18 deletions src/content/reference/react/hooks.md
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Expand Up @@ -106,24 +106,6 @@ To prioritize rendering, use one of these Hooks:
---
## Resource Hooks {/*resource-hooks*/}
*Resources* can be accessed by a component without having them as part of their state. For example, a component can read a message from a Promise or read styling information from a context.
To read a value from a resource, use this Hook:
- [`use`](/reference/react/use) lets you read the value of a resource like a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).
```js
function MessageComponent({ messagePromise }) {
const message = use(messagePromise);
const theme = use(ThemeContext);
// ...
}
```
---
## Other Hooks {/*other-hooks*/}
These Hooks are mostly useful to library authors and aren't commonly used in the application code.
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30 changes: 15 additions & 15 deletions src/content/reference/react/use.md
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Expand Up @@ -5,13 +5,13 @@ canary: true

<Canary>

The `use` Hook is currently only available in React's Canary and experimental channels. Learn more about [React's release channels here](/community/versioning-policy#all-release-channels).
The `use` API is currently only available in React's Canary and experimental channels. Learn more about [React's release channels here](/community/versioning-policy#all-release-channels).

</Canary>

<Intro>

`use` is a React Hook that lets you read the value of a resource like a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).
`use` is a React API that lets you read the value of a resource like a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).

```js
const value = use(resource);
Expand All @@ -38,9 +38,9 @@ function MessageComponent({ messagePromise }) {
// ...
```
Unlike all other React Hooks, `use` can be called within loops and conditional statements like `if`. Like other React Hooks, the function that calls `use` must be a Component or Hook.
Unlike React Hooks, `use` can be called within loops and conditional statements like `if`. Like React Hooks, the function that calls `use` must be a Component or Hook.
When called with a Promise, the `use` Hook integrates with [`Suspense`](/reference/react/Suspense) and [error boundaries](/reference/react/Component#catching-rendering-errors-with-an-error-boundary). The component calling `use` *suspends* while the Promise passed to `use` is pending. If the component that calls `use` is wrapped in a Suspense boundary, the fallback will be displayed. Once the Promise is resolved, the Suspense fallback is replaced by the rendered components using the data returned by the `use` Hook. If the Promise passed to `use` is rejected, the fallback of the nearest Error Boundary will be displayed.
When called with a Promise, the `use` API integrates with [`Suspense`](/reference/react/Suspense) and [error boundaries](/reference/react/Component#catching-rendering-errors-with-an-error-boundary). The component calling `use` *suspends* while the Promise passed to `use` is pending. If the component that calls `use` is wrapped in a Suspense boundary, the fallback will be displayed. Once the Promise is resolved, the Suspense fallback is replaced by the rendered components using the data returned by the `use` API. If the Promise passed to `use` is rejected, the fallback of the nearest Error Boundary will be displayed.
[See more examples below.](#usage)
Expand All @@ -50,11 +50,11 @@ When called with a Promise, the `use` Hook integrates with [`Suspense`](/referen
#### Returns {/*returns*/}
The `use` Hook returns the value that was read from the resource like the resolved value of a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).
The `use` API returns the value that was read from the resource like the resolved value of a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or [context](/learn/passing-data-deeply-with-context).
#### Caveats {/*caveats*/}
* The `use` Hook must be called inside a Component or a Hook.
* The `use` API must be called inside a Component or a Hook.
* When fetching data in a [Server Component](/reference/react/use-server), prefer `async` and `await` over `use`. `async` and `await` pick up rendering from the point where `await` was invoked, whereas `use` re-renders the component after the data is resolved.
* Prefer creating Promises in [Server Components](/reference/react/use-server) and passing them to [Client Components](/reference/react/use-client) over creating Promises in Client Components. Promises created in Client Components are recreated on every render. Promises passed from a Server Component to a Client Component are stable across re-renders. [See this example](#streaming-data-from-server-to-client).
Expand Down Expand Up @@ -230,7 +230,7 @@ export default function App() {
}
```
The <CodeStep step={2}>Client Component</CodeStep> then takes <CodeStep step={4}>the Promise it received as a prop</CodeStep> and passes it to the <CodeStep step={5}>`use`</CodeStep> Hook. This allows the <CodeStep step={2}>Client Component</CodeStep> to read the value from <CodeStep step={4}>the Promise</CodeStep> that was initially created by the Server Component.
The <CodeStep step={2}>Client Component</CodeStep> then takes <CodeStep step={4}>the Promise it received as a prop</CodeStep> and passes it to the <CodeStep step={5}>`use`</CodeStep> API. This allows the <CodeStep step={2}>Client Component</CodeStep> to read the value from <CodeStep step={4}>the Promise</CodeStep> that was initially created by the Server Component.
```js [[2, 6, "Message"], [4, 6, "messagePromise"], [4, 7, "messagePromise"], [5, 7, "use"]]
// message.js
Expand All @@ -243,7 +243,7 @@ export function Message({ messagePromise }) {
return <p>Here is the message: {messageContent}</p>;
}
```
Because <CodeStep step={2}>`Message`</CodeStep> is wrapped in <CodeStep step={3}>[`Suspense`](/reference/react/Suspense)</CodeStep>, the fallback will be displayed until the Promise is resolved. When the Promise is resolved, the value will be read by the <CodeStep step={5}>`use`</CodeStep> Hook and the <CodeStep step={2}>`Message`</CodeStep> component will replace the Suspense fallback.
Because <CodeStep step={2}>`Message`</CodeStep> is wrapped in <CodeStep step={3}>[`Suspense`](/reference/react/Suspense)</CodeStep>, the fallback will be displayed until the Promise is resolved. When the Promise is resolved, the value will be read by the <CodeStep step={5}>`use`</CodeStep> API and the <CodeStep step={2}>`Message`</CodeStep> component will replace the Suspense fallback.
<Sandpack>
Expand Down Expand Up @@ -293,7 +293,7 @@ export default function App() {
```js src/index.js hidden
// TODO: update to import from stable
// react instead of canary once the `use`
// Hook is in a stable release of React
// API is in a stable release of React
import React, { StrictMode } from 'react';
import { createRoot } from 'react-dom/client';
import './styles.css';
Expand Down Expand Up @@ -334,7 +334,7 @@ When passing a Promise from a Server Component to a Client Component, its resolv
#### Should I resolve a Promise in a Server or Client Component? {/*resolve-promise-in-server-or-client-component*/}
A Promise can be passed from a Server Component to a Client Component and resolved in the Client Component with the `use` Hook. You can also resolve the Promise in a Server Component with `await` and pass the required data to the Client Component as a prop.
A Promise can be passed from a Server Component to a Client Component and resolved in the Client Component with the `use` API. You can also resolve the Promise in a Server Component with `await` and pass the required data to the Client Component as a prop.
```js
export default async function App() {
Expand All @@ -360,7 +360,7 @@ In some cases a Promise passed to `use` could be rejected. You can handle reject
#### Displaying an error to users with an error boundary {/*displaying-an-error-to-users-with-error-boundary*/}
If you'd like to display an error to your users when a Promise is rejected, you can use an [error boundary](/reference/react/Component#catching-rendering-errors-with-an-error-boundary). To use an error boundary, wrap the component where you are calling the `use` Hook in an error boundary. If the Promise passed to `use` is rejected the fallback for the error boundary will be displayed.
If you'd like to display an error to your users when a Promise is rejected, you can use an [error boundary](/reference/react/Component#catching-rendering-errors-with-an-error-boundary). To use an error boundary, wrap the component where you are calling the `use` API in an error boundary. If the Promise passed to `use` is rejected the fallback for the error boundary will be displayed.
<Sandpack>
Expand Down Expand Up @@ -413,7 +413,7 @@ export default function App() {
```js src/index.js hidden
// TODO: update to import from stable
// react instead of canary once the `use`
// Hook is in a stable release of React
// API is in a stable release of React
import React, { StrictMode } from 'react';
import { createRoot } from 'react-dom/client';
import './styles.css';
Expand Down Expand Up @@ -474,9 +474,9 @@ To use the Promise's <CodeStep step={1}>`catch`</CodeStep> method, call <CodeSte
### "Suspense Exception: This is not a real error!" {/*suspense-exception-error*/}
You are either calling `use` outside of a React component or Hook function, or calling `use` in a try–catch block. If you are calling `use` inside a try–catch block, wrap your component in an error boundary, or call the Promise's `catch` to catch the error and resolve the Promise with another value. [See these examples](#dealing-with-rejected-promises).
You are either calling `use` outside of a React Component or Hook function, or calling `use` in a try–catch block. If you are calling `use` inside a try–catch block, wrap your component in an error boundary, or call the Promise's `catch` to catch the error and resolve the Promise with another value. [See these examples](#dealing-with-rejected-promises).
If you are calling `use` outside a React component or Hook function, move the `use` call to a React component or Hook function.
If you are calling `use` outside a React Component or Hook function, move the `use` call to a React Component or Hook function.
```jsx
function MessageComponent({messagePromise}) {
Expand All @@ -486,7 +486,7 @@ function MessageComponent({messagePromise}) {
// ...
```
Instead, call `use` outside any component closures, where the function that calls `use` is a component or Hook.
Instead, call `use` outside any component closures, where the function that calls `use` is a Component or Hook.
```jsx
function MessageComponent({messagePromise}) {
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10 changes: 5 additions & 5 deletions src/sidebarReference.json
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Expand Up @@ -14,11 +14,6 @@
"title": "Hooks",
"path": "/reference/react/hooks",
"routes": [
{
"title": "use",
"path": "/reference/react/use",
"canary": true
},
{
"title": "useCallback",
"path": "/reference/react/useCallback"
Expand Down Expand Up @@ -137,6 +132,11 @@
"title": "startTransition",
"path": "/reference/react/startTransition"
},
{
"title": "use",
"path": "/reference/react/use",
"canary": true
},
{
"title": "experimental_taintObjectReference",
"path": "/reference/react/experimental_taintObjectReference",
Expand Down

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