diff --git a/src/components/ButtonLink.tsx b/src/components/ButtonLink.tsx
index bd98d5b38..dff09ed3a 100644
--- a/src/components/ButtonLink.tsx
+++ b/src/components/ButtonLink.tsx
@@ -33,7 +33,7 @@ function ButtonLink({
className,
'active:scale-[.98] transition-transform inline-flex font-bold items-center outline-none focus:outline-none focus-visible:outline focus-visible:outline-link focus:outline-offset-2 focus-visible:dark:focus:outline-link-dark leading-snug',
{
- 'bg-link text-white dark:bg-brand-dark dark:text-secondary hover:bg-opacity-80':
+ 'bg-link text-white dark:bg-brand-dark dark:text-gray-90 hover:bg-opacity-80':
type === 'primary',
'text-primary dark:text-primary-dark shadow-secondary-button-stroke dark:shadow-secondary-button-stroke-dark hover:bg-gray-40/5 active:bg-gray-40/10 hover:dark:bg-gray-60/5 active:dark:bg-gray-60/10':
type === 'secondary',
diff --git a/src/content/reference/react-dom/components/form.md b/src/content/reference/react-dom/components/form.md
index 1043b13a0..10e9c6794 100644
--- a/src/content/reference/react-dom/components/form.md
+++ b/src/content/reference/react-dom/components/form.md
@@ -48,9 +48,47 @@ To create interactive controls for submitting information, render the [built-in
## Usage {/*usage*/}
-### Handle form submission on the client {/*handle-form-submission-on-the-client*/}
+### Handle form submission with an event handler {/*handle-form-submission-with-an-event-handler*/}
-Pass a function to the `action` prop of form to run the function when the form is submitted. [`formData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) will be passed to the function as an argument so you can access the data submitted by the form. This differs from the conventional [HTML action](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/form#action), which only accepts URLs. After the `action` function succeeds, all uncontrolled field elements in the form are reset.
+Pass a function to the `onSubmit` event handler to run code when the form is submitted. By default, the browser sends the form data to the current URL and refreshes the page, so call [`e.preventDefault()`](https://developer.mozilla.org/en-US/docs/Web/API/Event/preventDefault) to override that behavior.
+
+This example reads the submitted values with [`new FormData(e.target)`](https://developer.mozilla.org/en-US/docs/Web/API/FormData), which collects every field by its `name`. This keeps the inputs [uncontrolled](/reference/react-dom/components/input#reading-the-input-values-when-submitting-a-form). If you instead [control an input with state](/reference/react-dom/components/input#controlling-an-input-with-a-state-variable), read from that state on submit rather than from `FormData`.
+
+
+
+```js src/App.js
+export default function Search() {
+ function handleSubmit(e) {
+ // Prevent the browser from reloading the page
+ e.preventDefault();
+
+ // Read the form data
+ const form = e.target;
+ const formData = new FormData(form);
+ const query = formData.get("query");
+ alert(`You searched for '${query}'`);
+ }
+
+ return (
+
+ );
+}
+```
+
+
+
+
+
+Reading form data with `onSubmit` works in every version of React and gives you direct access to the [submit event](https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/submit_event), so you can call `e.preventDefault()` and read the data yourself. Passing the function to the `action` prop instead runs the submission in a [Transition](/reference/react/useTransition). React then tracks the pending state, sends thrown errors to the nearest error boundary, and lets the form work with [`useActionState`](/reference/react/useActionState) and [`useOptimistic`](/reference/react/useOptimistic). An `action` can also be a [Server Function](/reference/rsc/server-functions), which `onSubmit` does not support.
+
+
+
+### Handle form submission with an action prop {/*handle-form-submission-with-an-action-prop*/}
+
+Pass a function to the `action` prop of form to run the function when the form is submitted. [`formData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) will be passed to the function as an argument so you can access the data submitted by the form. This differs from the conventional [HTML action](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/form#action), which only accepts URLs. Unlike `onSubmit`, an `action` runs in a [Transition](/reference/react/useTransition) and calling `e.preventDefault()` isn't needed. After the `action` function succeeds, all uncontrolled field elements in the form are reset.
diff --git a/src/content/reference/react/Component.md b/src/content/reference/react/Component.md
index 3b882f097..f6c8cc4bf 100644
--- a/src/content/reference/react/Component.md
+++ b/src/content/reference/react/Component.md
@@ -1009,7 +1009,7 @@ Deriving state leads to verbose code and makes your components difficult to thin
#### Caveats {/*static-getderivedstatefromprops-caveats*/}
-- This method is fired on *every* render, regardless of the cause. This is different from [`UNSAFE_componentWillReceiveProps`](#unsafe_cmoponentwillreceiveprops), which only fires when the parent causes a re-render and not as a result of a local `setState`.
+- This method is fired on *every* render, regardless of the cause. This is different from [`UNSAFE_componentWillReceiveProps`](#unsafe_componentwillreceiveprops), which only fires when the parent causes a re-render and not as a result of a local `setState`.
- This method doesn't have access to the component instance. If you'd like, you can reuse some code between `static getDerivedStateFromProps` and the other class methods by extracting pure functions of the component props and state outside the class definition.
diff --git a/src/content/reference/react/use.md b/src/content/reference/react/use.md
index c13ad5203..1780f82e7 100644
--- a/src/content/reference/react/use.md
+++ b/src/content/reference/react/use.md
@@ -4,7 +4,7 @@ title: use
-`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).
+`use` is a React API that lets you read the 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).
```js
const value = use(resource);
@@ -18,46 +18,73 @@ const value = use(resource);
## Reference {/*reference*/}
-### `use(resource)` {/*use*/}
+### `use(context)` {/*use-context*/}
-Call `use` in your component to 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).
+Call `use` with a [context](/learn/passing-data-deeply-with-context) to read its value. Unlike [`useContext`](/reference/react/useContext), `use` can be called within loops and conditional statements like `if`.
-```jsx
+```js
import { use } from 'react';
-function MessageComponent({ messagePromise }) {
- const message = use(messagePromise);
+function Button() {
const theme = use(ThemeContext);
// ...
```
-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.
+[See more examples below.](#usage-context)
+
+#### Parameters {/*context-parameters*/}
-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.
+* `context`: A [context](/learn/passing-data-deeply-with-context) created with [`createContext`](/reference/react/createContext).
-[See more examples below.](#usage)
+#### Returns {/*context-returns*/}
-#### Parameters {/*parameters*/}
+The context value for the passed context, determined by the closest context provider above the calling component. If there is no provider, the returned value is the `defaultValue` passed to [`createContext`](/reference/react/createContext).
-* `resource`: this is the source of the data you want to read a value from. A resource can be a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) or a [context](/learn/passing-data-deeply-with-context).
+#### Caveats {/*context-caveats*/}
-#### Returns {/*returns*/}
+* `use` must be called inside a Component or a Hook.
+* Reading context with `use` is not supported in [Server Components](/reference/rsc/server-components).
+
+---
-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).
+### `use(promise)` {/*use-promise*/}
-#### Caveats {/*caveats*/}
+Call `use` with a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) to read its resolved value. The component calling `use` *suspends* while the Promise is pending. Despite its name, `use` is not a Hook. Unlike Hooks, it can be called inside loops and conditional statements like `if`.
-* The `use` API must be called inside a Component or a Hook.
-* When fetching data in a [Server Component](/reference/rsc/server-components), 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/rsc/server-components) and passing them to [Client Components](/reference/rsc/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).
+```js
+import { use } from 'react';
+
+function MessageComponent({ messagePromise }) {
+ const message = use(messagePromise);
+ // ...
+```
+
+If the component that calls `use` is wrapped in a [Suspense](/reference/react/Suspense) boundary, the fallback will be displayed while the Promise is pending. Once the Promise is resolved, the Suspense fallback is replaced by the rendered components using the data returned by `use`. If the Promise is rejected, the fallback of the nearest [Error Boundary](/reference/react/Component#catching-rendering-errors-with-an-error-boundary) will be displayed.
+
+[See more examples below.](#usage-promises)
+
+#### Parameters {/*promise-parameters*/}
+
+* `promise`: A [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) whose resolved value you want to read. The Promise must be [cached](#caching-promises-for-client-components) so that the same instance is reused across re-renders.
+
+#### Returns {/*promise-returns*/}
+
+The resolved value of the Promise.
+
+#### Caveats {/*promise-caveats*/}
+
+* `use` must be called inside a Component or a Hook.
+* `use` cannot be called inside a try-catch block. Instead, wrap your component in an [Error Boundary](#displaying-an-error-with-an-error-boundary) to catch the error and display a fallback.
+* Promises passed to `use` must be cached so the same Promise instance is reused across re-renders. [See caching Promises below.](#caching-promises-for-client-components)
+* When passing a Promise from a Server Component to a Client Component, its resolved value must be [serializable](/reference/rsc/use-client#serializable-types).
---
-## Usage {/*usage*/}
+## Usage (Context) {/*usage-context*/}
### Reading context with `use` {/*reading-context-with-use*/}
-When a [context](/learn/passing-data-deeply-with-context) is passed to `use`, it works similarly to [`useContext`](/reference/react/useContext). While `useContext` must be called at the top level of your component, `use` can be called inside conditionals like `if` and loops like `for`. `use` is preferred over `useContext` because it is more flexible.
+When a [context](/learn/passing-data-deeply-with-context) is passed to `use`, it works similarly to [`useContext`](/reference/react/useContext). While `useContext` must be called at the top level of your component, `use` can be called inside conditionals like `if` and loops like `for`.
```js [[2, 4, "theme"], [1, 4, "ThemeContext"]]
import { use } from 'react';
@@ -194,11 +221,801 @@ function Button({ show, children }) {
-### Streaming data from the server to the client {/*streaming-data-from-server-to-client*/}
+### Reading a Promise from context {/*reading-a-promise-from-context*/}
+
+To share asynchronous data without prop drilling, set a Promise as a context value, then read it with `use(context)` and resolve it with `use(promise)`:
+
+```js
+import { use } from 'react';
+import { UserContext } from './UserContext';
+
+function Profile() {
+ const userPromise = use(UserContext);
+ const user = use(userPromise);
+ return
{user.name}
;
+}
+```
+
+Reading the value requires two `use` calls because the context value itself isn't awaited. See [Before you use context](/learn/passing-data-deeply-with-context#before-you-use-context) for alternatives to consider before reaching for context.
+
+Wrap the components that read the Promise in a [Suspense](/reference/react/Suspense) boundary so only that subtree suspends while the Promise is pending. See [Usage (Promises)](#usage-promises) below for more on reading Promises with `use`.
+
+
+
+When this pattern is used with [Server Components](/reference/rsc/server-components), refetching the Promise requires refetching the Server Component that sets the Promise in context. Avoid setting the Promise in context high in the tree, since that would refetch large parts of the app unnecessarily.
+
+
+
+---
+
+## Usage (Promises) {/*usage-promises*/}
+
+### Reading a Promise with `use` {/*reading-a-promise-with-use*/}
+
+Call `use` with a Promise to read its resolved value. The component will [suspend](/reference/react/Suspense) while the Promise is pending.
+
+```js [[1, 4, "use(albumsPromise)"]]
+import { use } from 'react';
+
+function Albums({ albumsPromise }) {
+ const albums = use(albumsPromise);
+ return (
+
+ {albums.map(album => (
+
+ {album.title} ({album.year})
+
+ ))}
+
+ );
+}
+```
+
+Wrap the component that calls `use` in a [Suspense](/reference/react/Suspense) boundary so React can show a fallback while the Promise is pending. The closest Suspense boundary above the suspending component shows its fallback. Once the Promise resolves, React reads the value with `use` and replaces the fallback with the rendered component.
+
+
+
+#### Fetching data with `use` {/*fetching-data-with-use*/}
+
+In this example, `Albums` calls `use` with a cached Promise. The component suspends while the Promise is pending, and React displays the nearest Suspense fallback. Rejected Promises propagate to the nearest [Error Boundary](/reference/react/Component#catching-rendering-errors-with-an-error-boundary).
+
+
+
+```js src/App.js active
+import { use, Suspense } from 'react';
+import { ErrorBoundary } from 'react-error-boundary';
+import { fetchData } from './data.js';
+
+export default function App() {
+ return (
+ Could not fetch albums.}>
+ }>
+
+
+
+ );
+}
+
+function Albums() {
+ const albums = use(fetchData('/albums'));
+ return (
+
+ {albums.map(album => (
+
+ {album.title} ({album.year})
+
+ ))}
+
+ );
+}
+
+function Loading() {
+ return
Loading...
;
+}
+```
+
+```js src/data.js hidden
+// Note: the way you would do data fetching depends on
+// the framework that you use together with Suspense.
+// Normally, the caching logic would be inside a framework.
+
+let cache = new Map();
+
+export function fetchData(url) {
+ if (!cache.has(url)) {
+ cache.set(url, getData(url));
+ }
+ return cache.get(url);
+}
+
+async function getData(url) {
+ if (url === '/albums') {
+ return await getAlbums();
+ } else {
+ throw Error('Not implemented');
+ }
+}
+
+async function getAlbums() {
+ // Add a fake delay to make waiting noticeable.
+ await new Promise(resolve => {
+ setTimeout(resolve, 1000);
+ });
+
+ return [{
+ id: 13,
+ title: 'Let It Be',
+ year: 1970
+ }, {
+ id: 12,
+ title: 'Abbey Road',
+ year: 1969
+ }, {
+ id: 11,
+ title: 'Yellow Submarine',
+ year: 1969
+ }, {
+ id: 10,
+ title: 'The Beatles',
+ year: 1968
+ }];
+}
+```
+
+```json package.json hidden
+{
+ "dependencies": {
+ "react": "19.0.0",
+ "react-dom": "19.0.0",
+ "react-scripts": "^5.0.0",
+ "react-error-boundary": "4.0.3"
+ },
+ "main": "/index.js"
+}
+```
+
+
+
+
+
+#### Fetching data with `useEffect` {/*fetching-data-with-useeffect*/}
+
+Before `use`, a common approach was to fetch data in an Effect and update state when the data arrives. Compared to `use`, this approach requires managing loading and error states manually. For more details on why fetching in an Effect is discouraged, see [You Might Not Need an Effect](/learn/you-might-not-need-an-effect#fetching-data).
+
+
+
+```js src/App.js active
+import { useState, useEffect } from 'react';
+import { fetchAlbums } from './data.js';
+
+export default function App() {
+ const [albums, setAlbums] = useState(null);
+ const [isLoading, setIsLoading] = useState(true);
+ const [error, setError] = useState(null);
+
+ useEffect(() => {
+ fetchAlbums()
+ .then(data => {
+ setAlbums(data);
+ setIsLoading(false);
+ })
+ .catch(err => {
+ setError(err);
+ setIsLoading(false);
+ });
+ }, []);
+
+ if (isLoading) {
+ return
Loading...
;
+ }
+
+ if (error) {
+ return
Error: {error.message}
;
+ }
+
+ return (
+
+ {albums.map(album => (
+
+ {album.title} ({album.year})
+
+ ))}
+
+ );
+}
+```
+
+```js src/data.js hidden
+export async function fetchAlbums() {
+ // Add a fake delay to make waiting noticeable.
+ await new Promise(resolve => {
+ setTimeout(resolve, 1000);
+ });
+
+ return [{
+ id: 13,
+ title: 'Let It Be',
+ year: 1970
+ }, {
+ id: 12,
+ title: 'Abbey Road',
+ year: 1969
+ }, {
+ id: 11,
+ title: 'Yellow Submarine',
+ year: 1969
+ }, {
+ id: 10,
+ title: 'The Beatles',
+ year: 1968
+ }];
+}
+```
+
+
+
+
+
+
+
+
+
+##### Promises passed to `use` must be cached {/*promises-must-cached*/}
+
+Promises created during render are recreated on every render, which causes React to show the Suspense fallback repeatedly and prevents content from appearing.
+
+```js
+function Albums() {
+ // 🔴 `fetch` creates a new Promise on every render.
+ const albums = use(fetch('/albums'));
+ // ...
+}
+```
+
+Instead, pass a Promise from a cache, a Suspense-enabled framework, or a Server Component:
+
+```js
+// ✅ fetchData reads the Promise from a cache.
+const albums = use(fetchData('/albums'));
+```
+
+
+
+
+
+#### Why are Promises recreated on every render? {/*why-promises-recreated*/}
+
+[React doesn't preserve state for renders that suspended before mounting](/reference/react/Suspense#caveats). After each suspension, React retries rendering from scratch, so any Promise created during render is recreated.
+
+Common ways a Promise can be unintentionally recreated during render:
+
+```js
+function Albums() {
+ // 🔴 `fetch` creates a new Promise on every render.
+ const albums = use(fetch('/albums'));
+
+ // 🔴 Uncached `async` function calls create a new Promise on every render.
+ const albums = use((async () => {
+ const res = await fetch('/albums');
+ return res.json();
+ })());
+
+ // 🔴 Adding `.then` returns a new Promise on every render,
+ // even if `fetchData` is cached.
+ const albums = use(fetchData('/albums').then(res => res.json()));
+ // ...
+}
+```
+
+Ideally, Promises are created before rendering, such as in an event handler, a route loader, or a Server Component, and passed to the component that calls `use`. Fetching lazily in render delays network requests and can create waterfalls.
+
+```js
+// ✅ fetchData reads the Promise from a cache.
+const albums = use(fetchData('/albums'));
+```
+
+
+
+---
+
+### Caching Promises for Client Components {/*caching-promises-for-client-components*/}
+
+Promises passed to `use` in Client Components must be cached so the same Promise instance is reused across re-renders. If a new Promise is created directly in render, React will display the Suspense fallback on every re-render.
+
+```js
+// ✅ Cache the Promise so the same one is reused across renders
+let cache = new Map();
+
+export function fetchData(url) {
+ if (!cache.has(url)) {
+ cache.set(url, getData(url));
+ }
+ return cache.get(url);
+}
+```
+
+The `fetchData` function returns the same Promise each time it's called with the same URL. When `use` receives the same Promise on a re-render, it reads the already-resolved value synchronously without suspending.
+
+
+
+The way you cache Promises depends on the framework you use with Suspense. Frameworks typically provide built-in caching mechanisms. If you don't use a framework, you can use a simple module-level cache like the one above, or a [Suspense-enabled data source](/reference/react/Suspense#displaying-a-fallback-while-content-is-loading).
+
+
+
+In the example below, clicking "Re-render" updates state in `App` and triggers a re-render. Because `fetchData` returns the same cached Promise, `Albums` reads the value synchronously instead of showing the Suspense fallback again.
+
+
+
+```js src/App.js active
+import { use, Suspense, useState } from 'react';
+import { fetchData } from './data.js';
+
+export default function App() {
+ const [count, setCount] = useState(0);
+ return (
+ <>
+
+
+ );
+}
+```
+
+```js src/data.js hidden
+// Note: the way you would do data fetching depends on
+// the framework that you use together with Suspense.
+// Normally, the caching logic would be inside a framework.
+
+let cache = new Map();
+
+export function fetchData(url) {
+ if (!cache.has(url)) {
+ cache.set(url, getData(url));
+ }
+ return cache.get(url);
+}
+
+async function getData(url) {
+ if (url === '/albums') {
+ return await getAlbums();
+ } else {
+ throw Error('Not implemented');
+ }
+}
+
+async function getAlbums() {
+ // Add a fake delay to make waiting noticeable.
+ await new Promise(resolve => {
+ setTimeout(resolve, 1000);
+ });
+
+ return [{
+ id: 13,
+ title: 'Let It Be',
+ year: 1970
+ }, {
+ id: 12,
+ title: 'Abbey Road',
+ year: 1969
+ }, {
+ id: 11,
+ title: 'Yellow Submarine',
+ year: 1969
+ }];
+}
+```
+
+
+
+
+
+#### How to implement a promise cache {/*how-to-implement-a-promise-cache*/}
+
+A basic cache stores the Promise keyed by URL so the same instance is reused across renders. To also avoid unnecessary Suspense fallbacks when data is already available, you can set `status` and `value` (or `reason`) fields on the Promise. React checks these fields when `use` is called: if `status` is `'fulfilled'`, it reads `value` synchronously without suspending. If `status` is `'rejected'`, it throws `reason`. If the field is missing or `'pending'`, it suspends.
+
+```js
+let cache = new Map();
+
+function fetchData(url) {
+ if (!cache.has(url)) {
+ const promise = getData(url);
+ promise.status = 'pending';
+ promise.then(
+ value => {
+ promise.status = 'fulfilled';
+ promise.value = value;
+ },
+ reason => {
+ promise.status = 'rejected';
+ promise.reason = reason;
+ },
+ );
+ cache.set(url, promise);
+ }
+ return cache.get(url);
+}
+```
+
+This is primarily useful for library authors building Suspense-compatible data layers. React will set the `status` field itself on Promises that don't have it, but setting it yourself avoids an extra render when the data is already available.
+
+This cache pattern is the foundation for [re-fetching data](#re-fetching-data-in-client-components) (where changing the cache key triggers a new fetch) and [preloading data on hover](#preloading-data-on-hover) (where calling `fetchData` early means the Promise may already be resolved by the time `use` reads it).
+
+
+
+
+
+Don't skip calling `use` based on whether a Promise is already settled.
+
+Unlike other hooks, `use` can be called inside conditions and loops — but it must always be called for the Promise itself. Never read `promise.status` or `promise.value` directly to bypass `use`; always pass the Promise to `use` and let React handle it.
+
+
+```js
+// 🔴 Don't bypass `use` by reading promise status directly
+if (promise.status === 'fulfilled') {
+ return promise.value;
+}
+const value = use(promise);
+```
+
+```js
+// ✅ Pass the promise to `use` and let React track the promise
+const value = use(promise);
+```
+
+Bypassing `use` this way can break React Suspense optimizations and Suspense features for React DevTools. You can `use(promise)` conditionally, but don't conditionally `use(promise)` based on the promise itself.
+
+
+
+---
+
+### Re-fetching data in Client Components {/*re-fetching-data-in-client-components*/}
+
+To refresh data at the same URL (for example, with a "Refresh" button), invalidate the cache entry and start a new fetch inside a [`startTransition`](/reference/react/startTransition). Store the resulting Promise in state to trigger a re-render. While the new Promise is pending, React keeps showing the existing content because the update is inside a Transition.
+
+```js
+function App() {
+ const [albumsPromise, setAlbumsPromise] = useState(fetchData('/albums'));
+ const [isPending, startTransition] = useTransition();
+
+ function handleRefresh() {
+ startTransition(() => {
+ setAlbumsPromise(refetchData('/albums'));
+ });
+ }
+ // ...
+}
+```
+
+`refetchData` clears the old cache entry and starts a new fetch at the same URL. Storing the resulting Promise in state triggers a re-render inside the Transition. On re-render, `Albums` receives the new Promise and `use` suspends on it while React keeps showing the old content.
+
+
+
+```js src/App.js active
+import { Suspense, useState, useTransition } from 'react';
+import { use } from 'react';
+import { fetchData, refetchData } from './data.js';
+
+export default function App() {
+ const [albumsPromise, setAlbumsPromise] = useState(
+ () => fetchData('/the-beatles/albums')
+ );
+ const [isPending, startTransition] = useTransition();
+
+ function handleRefresh() {
+ startTransition(() => {
+ setAlbumsPromise(refetchData('/the-beatles/albums'));
+ });
+ }
+
+ return (
+ <>
+
+
;
+}
+```
+
+```js src/data.js hidden
+// Note: the way you would do data fetching depends on
+// the framework that you use together with Suspense.
+// Normally, the caching logic would be inside a framework.
+
+let cache = new Map();
+
+export function fetchData(url) {
+ if (!cache.has(url)) {
+ cache.set(url, getData(url));
+ }
+ return cache.get(url);
+}
+
+export function refetchData(url) {
+ cache.delete(url);
+ return fetchData(url);
+}
+
+async function getData(url) {
+ if (url.startsWith('/the-beatles/albums')) {
+ return await getAlbums();
+ } else {
+ throw Error('Not implemented');
+ }
+}
+
+async function getAlbums() {
+ // Add a fake delay to make waiting noticeable.
+ await new Promise(resolve => {
+ setTimeout(resolve, 1000);
+ });
+
+ return [{
+ id: 13,
+ title: 'Let It Be',
+ year: 1970
+ }, {
+ id: 12,
+ title: 'Abbey Road',
+ year: 1969
+ }, {
+ id: 11,
+ title: 'Yellow Submarine',
+ year: 1969
+ }, {
+ id: 10,
+ title: 'The Beatles',
+ year: 1968
+ }, {
+ id: 9,
+ title: 'Magical Mystery Tour',
+ year: 1967
+ }];
+}
+```
+
+```css
+button { margin-bottom: 10px; }
+```
+
+
+
+
+
+Frameworks that support Suspense typically provide their own caching and invalidation mechanisms. The custom cache above is useful for understanding the pattern, but in practice prefer your framework's data fetching solution.
+
+
+
+---
+
+### Preloading data on hover {/*preloading-data-on-hover*/}
+
+You can start loading data before it's needed by calling `fetchData` during a hover event. Since `fetchData` caches the Promise, the data may already be available by the time the user clicks. If the Promise has resolved by the time `use` reads it, React renders the component immediately without showing a Suspense fallback.
+
+```js
+