Document ViewTransitions API reference

src/content/docs/en/reference/api-reference.mdx

@@ -2137,6 +2137,355 @@ export const onRequest = defineMiddleware(async (context, next) => {
 })
 ```
 
+## View Transitions client API (`astro:transitions/client`)
+
+<p><Since v="3.2.0" /></p>
+
+This module provides functions to control and interact with the View Transitions and client-side router.
+
+For features and usage examples, [see our View Transitions guide](/en/guides/view-transitions/).
+
+### `navigate()`
+
+<p>
+
+**Type:** `(href: string, options?: Options) => void`<br />
+<Since v="3.2.0" />
+</p>
+
+Start a navigation to the given `href` using View Transitions.
+
+This function signature is based on the [`navigate` function from the browser Navigation API](https://developer.mozilla.org/en-US/docs/Web/API/Navigation/navigate). Although based on the Navigation API, this function is implemented on top of the [History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API) to allow for navigation without reloading the page.
+
+#### `history` option
+
+<p>
+
+**Type:** `'auto' | 'push' | 'replace'`<br />
+**Default:** `'auto'`<br />
+<Since v="3.2.0" />
+</p>
+
+Defines how this navigation should be added to the browser history.
+
+- `'push'`: the router will use `history.pushState` to create a new entry in the browser history.
+- `'replace'`: the router will use `history.replaceState` to update the URL without adding a new entry into navigation.
+- `'auto'` (default): the router will attempt `history.pushState`, but if the URL cannot be transitioned to, the current URL will remain with no changes to the browser history.
+
+This option follows the [`history` option](https://developer.mozilla.org/en-US/docs/Web/API/Navigation/navigate#history) from the browser Navigation API but simplified for the cases that can happen on an Astro project.
+
+#### `formData` option
+
+<p>
+
+**Type:** `FormData`<br />
+<Since v="3.5.0" />
+</p>
+
+A `FormData` object for `POST` requests.
+
+When this option is given, the requests to the navigation target page will be sent as a `POST` request with the given form data object as the content.
+
+Submitting an HTML form with View Transitions enabled will use this method instead of the default navigation with page reload. Calling this method allows triggering the same behavior programmatically.
+
+#### `info` option
+
+<p>
+
+**Type:** `any`<br />
+<Since v="3.6.0" />
+</p>
+
+Arbitrary data to be included in the `astro:before-preparation` and `astro:before-swap` events caused by this navigation.
+
+This option mimics the [`info` option](https://developer.mozilla.org/en-US/docs/Web/API/Navigation/navigate#info) from the browser Navigation API.
+
+#### `state` option
+
+<p>
+
+**Type:** `any`<br />
+<Since v="3.6.0" />
+</p>
+
+Arbitrary data to be associated with the `NavitationHistoryEntry` object created by this navigation. This data can then be retrieved using the [`history.getState` function](https://developer.mozilla.org/en-US/docs/Web/API/NavigationHistoryEntry/getState) from the History API.
+
+This option mimics the [`state` option](https://developer.mozilla.org/en-US/docs/Web/API/Navigation/navigate#state) from the browser Navigation API.
+
+#### `sourceElement` option
+
+<p>
+
+**Type:** `Element`<br />
+<Since v="3.6.0" />
+</p>
+
+The element that triggered this navigation, if any. This element will be available in the following events:
+- `astro:before-preparation`
+- `astro:before-swap`
+
+### `supportsViewTransitions`
+
+<p>
+
+**Type:** `boolean`<br />
+<Since v="3.2.0" />
+</p>
+
+A constant that indicates whether View Transitions are supported and enabled in the current browser.
+
+### `transitionEnabledOnThisPage`
+
+<p>
+
+**Type:** `boolean`<br />
+<Since v="3.2.0" />
+</p>
+
+Whether the current page has the View Transitions enabled for client-side navigation. This can be used to make reusable components that adapt to when they are used on pages with and without View Transitions.
+
+### `getFallback`
+
+<p>
+
+**Type:** `() => 'none' | 'animate' | 'swap'`<br />
+<Since v="3.6.0" />
+</p>
+
+Returns the fallback strategy for View Transitions.
+
+See the guide on [Fallback control](/en/guides/view-transitions/#fallback-control) for how to choose and configure the fallback behavior.
+
+## View Transition Events
+
+<p><Since v="3.6.0" /></p>
+
+### `astro:before-preparation` event
+
+An event dispatched at the beginning of a navigation using View Transitions. This event happens before any request is made and any browser state is changed.
+
+This event has the attributes:
+- [`info`](#info)
+- [`state`](#state-option)
+- [`sourceElement`](#sourceelement-option)
+- [`navigationType`](#navigationtype)
+- [`direction`](#direction)
+- [`from`](#from)
+- [`to`](#to)
+- [`formData`](#formdata)
+- [`loader`](#loader)
+
+Read more about how to use this event on the [View Transitions guide](/en/guides/view-transitions/#astrobefore-preparation).
+
+### `astro:after-preparation`
+
+An event dispatched after the next page in a navigation using View Transitions is loaded.
+
+This event has no attributes.
+
+Read more about how to use this event on the [View Transitions guide](/en/guides/view-transitions/#astroafter-preparation).
+
+### `astro:before-swap`
+
+An event dispatched after the next page is parsed, prepared, and linked into a document in preparation for the transition but before any content is swapped between the documents.
+
+This event can't be canceled. Calling `preventDefault()` is a no-op.
+
+This event has the attributes:
+- [`info`](#info)
+- [`state`](#state-option)
+- [`sourceElement`](#sourceelement-option)
+- [`navigationType`](#navigationtype)
+- [`direction`](#direction)
+- [`from`](#from)
+- [`to`](#to)
+- [`viewTransition`](#viewtransition)
+- [`swap`](#swap)
+
+Read more about how to use this event on the [View Transitions guide](/en/guides/view-transitions/#astrobefore-swap).
+
+### `astro:after-swap`
+
+An event dispatched after the contents of the page have been swapped but before the view transition ends.
+
+The history entry and scroll position have already been updated when this event is triggered.
+
+### `astro:page-load`
+
+An event dispatched after a page completes loading, be it from a navigation using view transitions or native to the browser.
+
+When view transitions is enabled on the page, code that would normally execute on `DOMContentLoaded` should be changed to execute on this event.
+
+### View Transitions events attributes
+
+<p><Since v="3.6.0" /></p>
+
+#### `info`
+
+<p>
+
+**Type:** `URL`
+</p>
+
+Arbitrary data defined during navigation.
+
+This is the literal value passed on the [`info` option](#info-option) of the [`navigate()` function](#navigate).
+
+#### `sourceElement`
+
+<p>
+
+**Type:** `Element | undefined`
+</p>
+
+The element that triggered the navigation. This can be, for example, an `<a>` element that was clicked.
+
+When using the [`navigate()` function](#navigate), this will be the element specified in the call.
+
+#### `newDocument`
+
+<p>
+
+**Type:** `Document`
+</p>
+
+The document for the next page in the navigation. The contents of this document will be swapped in place of the contents of the current document.
+
+#### `navigationType`
+
+<p>
+
+**Type:** `'push' | 'replace' | 'traverse'`
+</p>
+
+Which kind of history navigation is happening.
+- `push`: a new `NavigationHistoryEntry` is being created for the new page.
+- `replace`: the current `NavigationHistoryEntry` is being replaced with an entry for the new page.
+- `traverse`: no `NavigationHistoryEntry` is created. The position in the history is changing.
+  The direction of the traversal is given on the [`direction` attribute](#direction)
+
+#### `direction`
+
+<p>
+
+**Type:** `Direction`
+</p>
+
+The direction of the transition.
+- `forward`: navigating to the next page in the history or to a new page.
+- `back`: navigating to the previous page in the history.
+- Anything else some other listener might have set.
+
+#### `from`
+
+<p>
+
+**Type:** `URL`
+</p>
+
+The URL of the page initiating the navigation.
+
+#### `to`
+
+<p>
+
+**Type:** `URL`
+</p>
+
+The URL of the page being navigated to. This property can be modified, the value at the end of the lifecycle will be used in the `NavigationHistoryEntry` for the next page.
+
+#### `formData`
+
+<p>
+
+**Type:** `FormData | undefined`
+</p>
+
+A `FormData` object for `POST` requests.
+
+When this attribute is set, a `POST` request will be sent to the [`to` URL](#to) with the given form data object as the content instead of the normal `GET` request.
+
+When submitting an HTML form with View Transitions enabled, this field is automatically set to the data in the form. When using the [`navigate()` function](#navigate), this value is the same as given in the options.
+
+#### `loader`
+
+<p>
+
+**Type:** `() => Promise<void>`
+</p>
+
+Implementation of the following phase in the navigation (loading the next page). This implementation can be overridden to add extra behavior.
+
+#### `viewTransition`
+
+<p>
+
+**Type:** [`ViewTransition`](https://developer.mozilla.org/en-US/docs/Web/API/ViewTransition)
+</p>
+
+The view transition object used in this navigation. On browsers that do not support the [View Transitions API](https://developer.mozilla.org/en-US/docs/Web/API/View_Transitions_API), this is an object implementing the same API for convenience but without the DOM integration.
+
+#### `swap`
+
+<p>
+
+**Type:** `() => void`
+</p>
+
+Implementation of the document swap logic. 
+
+Read more on how to [build your own custom swap function](/en/guides/view-transitions/#building-a-custom-swap-function) on the View Transitions guide.
+
+By default, this implementation will call the following functions in order:
+
+##### `deselectScripts()`
+
+<p>
+
+**Type:** `(newDocument: Document) => void`
+</p>
+
+Marks scripts in the new document that should not be executed. Those scripts are already in the current document and are not flagged for re-execution using [`data-astro-rerun`](/en/guides/view-transitions/#data-astro-rerun).
+
+##### `swapRootAttributes()`
+
+<p>
+
+**Type:** `(newDocument: Document) => void`
+</p>
+
+Swaps the attributes between the document roots, like the `lang` attribute. This also includes Astro-injected internal attributes like `data-astro-transition`, which makes the transition direction available to Astro-generated CSS rules.
+
+When making a custom swap function, it is important to call this function so as not to break the view transition's animations.
+
+##### `swapHeadElements()`
+
+<p>
+
+**Type:** `(newDocument: Document) => void`
+</p>
+
+Removes every element from the current document's `<head>` that is not persisted to the new document. Then appends all new elements from the new document's `<head>` to the current document's `<head>`.
+
+##### `saveFocus()`
+
+<p>
+
+**Type:** `() => () => void`
+</p>
+
+Stores the element in focus on the current page and returns a function that when called, if the focused element was persisted, returns the focus to it.
+
+
+##### `swapBodyElements()`
+
+<p>
+
+**Type:** `(newBody: Element, oldBody: Element) => void`
+</p>
+
+Replaces the old body with the new body. Then, goes through every element in the old body that should be persisted and have a matching element in the new body and swaps the old element back in place.
+
 ## Actions (`astro:actions`)
 
 <p>