Add missing docs for requestFormReset API (#8576)

* Add requestFormReset React DOM reference page

* docs: cross-link automatic and manual form resets

* Restore unrelated upstream test formatting

Author: smg99

src/content/reference/react-dom/components/form.md

@@ -103,6 +103,8 @@ When you pass a function to `action`, React:
 * Propagates any errors to the nearest Error Boundary.
 * Resets the form's uncontrolled fields when the function succeeds. To keep their values, see [Preserving form values after an Action](#preserve-form-values-after-an-action).
 
+If you handle submission manually, you can [request the same reset behavior with `requestFormReset`](/reference/react-dom/requestFormReset#requesting-a-reset-in-a-custom-form-action).
+
 Because the Action runs in a Transition, you can also use [`useActionState`](/reference/react/useActionState) to manage form state and [`useOptimistic`](/reference/react/useOptimistic) for optimistic UI. For [Server Functions](/reference/rsc/server-functions) and progressive enhancement, see [Handling form submission with a Server Function](#handle-form-submission-with-a-server-function).
 
 <Sandpack>

src/content/reference/react-dom/index.md

@@ -16,6 +16,7 @@ These APIs can be imported from your components. They are rarely used:
 
 * [`createPortal`](/reference/react-dom/createPortal) lets you render child components in a different part of the DOM tree.
 * [`flushSync`](/reference/react-dom/flushSync) lets you force React to flush a state update and update the DOM synchronously.
+* [`requestFormReset`](/reference/react-dom/requestFormReset) lets you request a form reset when handling submissions with custom Actions or Transitions.
 
 ## Resource Preloading APIs {/*resource-preloading-apis*/}
 

src/content/reference/react-dom/requestFormReset.md

@@ -0,0 +1,89 @@
+---
+title: requestFormReset
+---
+
+<Intro>
+
+`requestFormReset` lets you reset a React-managed form after an Action or Transition finishes.
+
+```js
+requestFormReset(form)
+```
+
+</Intro>
+
+<InlineToc />
+
+---
+
+## Reference {/*reference*/}
+
+### `requestFormReset(form)` {/*requestformreset*/}
+
+Call `requestFormReset` to request that a form resets after the current Action or Transition completes.
+
+```js
+import { startTransition } from 'react';
+import { requestFormReset } from 'react-dom';
+
+function handleSubmit(form) {
+  startTransition(async () => {
+    const formData = new FormData(form);
+    requestFormReset(form);
+    await save(formData);
+  });
+}
+```
+
+[See more examples below.](#usage)
+
+#### Parameters {/*parameters*/}
+
+* `form`: an [HTML form element](https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement) rendered by React.
+
+#### Returns {/*returns*/}
+
+`requestFormReset` returns nothing.
+
+#### Caveats {/*caveats*/}
+
+* Pass a form element that is rendered by React. Passing a non-form element, or a form not managed by React, throws an error.
+* `requestFormReset` is intended for Actions and Transitions. If called outside an Action or Transition, React warns in development and performs a synchronous reset.
+* `requestFormReset` is useful when you implement form submission logic yourself (for example with `onSubmit` + `startTransition`) and still want React's form reset behavior.
+* This API requests a reset for uncontrolled form fields. For controlled fields, handle resets by updating state, such as in `onReset`.
+
+---
+
+## Usage {/*usage*/}
+
+### Requesting a reset in a custom form Action {/*requesting-a-reset-in-a-custom-form-action*/}
+
+React [automatically resets uncontrolled fields after a successful `<form action={...}>` submission](/reference/react-dom/components/form#handle-form-submission-with-an-action-prop). When you implement submission manually, you can opt into the same behavior by calling `requestFormReset`.
+
+```js
+import { startTransition } from 'react';
+import { requestFormReset } from 'react-dom';
+
+function SearchForm() {
+  async function onSubmit(event) {
+    event.preventDefault();
+
+    const form = event.currentTarget;
+    const formData = new FormData(form);
+
+    startTransition(async () => {
+      requestFormReset(form);
+      await submitSearch(formData);
+    });
+  }
+
+  return (
+    <form onSubmit={onSubmit}>
+      <input name="query" defaultValue="react" />
+      <button type="submit">Search</button>
+    </form>
+  );
+}
+```
+
+If your submission uses the built-in `<form action={...}>` behavior, you don't need to call `requestFormReset` manually.

src/sidebarReference.json

@@ -262,6 +262,10 @@
           "title": "flushSync",
           "path": "/reference/react-dom/flushSync"
         },
+        {
+          "title": "requestFormReset",
+          "path": "/reference/react-dom/requestFormReset"
+        },
         {
           "title": "preconnect",
           "path": "/reference/react-dom/preconnect"