docs: more Svelte 5 conversion (#12871)

---------

Co-authored-by: Ben McCann <[email protected]>
Co-authored-by: Willow (GHOST) <[email protected]>
Co-authored-by: Sri Senthil Balaji J <[email protected]>
Co-authored-by: Tee Ming <[email protected]>

Author: 5 people

documentation/docs/20-core-concepts/10-routing.md

@@ -37,17 +37,22 @@ A `+page.svelte` component defines a page of your app. By default, pages are ren
 <a href="/">Home</a>
 ```
 
+Pages can receive data from `load` functions via the `data` prop.
+
 ```svelte
 <!--- file: src/routes/blog/[slug]/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 </script>
 
 <h1>{data.title}</h1>
 <div>{@html data.content}</div>
 ```
 
+> [!LEGACY] In Svelte 4
+> In Svelte 4, you'd use `export let data` instead
+
 > [!NOTE] Note that SvelteKit uses `<a>` elements to navigate between routes, rather than a framework-specific `<Link>` component.
 
 ### +page.js
@@ -153,21 +158,29 @@ But in many apps, there are elements that should be visible on _every_ page, suc
 
 To create a layout that applies to every page, make a file called `src/routes/+layout.svelte`. The default layout (the one that SvelteKit uses if you don't bring your own) looks like this...
 
-```html
-<slot></slot>
+```svelte
+<script>
+	let { children } = $props();
+</script>
+
+{@render children()}
 ```
 
-...but we can add whatever markup, styles and behaviour we want. The only requirement is that the component includes a `<slot>` for the page content. For example, let's add a nav bar:
+...but we can add whatever markup, styles and behaviour we want. The only requirement is that the component includes a `@render` tag for the page content. For example, let's add a nav bar:
+
+```svelte
+<!---- file: src/routes/+layout.svelte --->
+<script>
+	let { children } = $props();
+</script>
 
-```html
-/// file: src/routes/+layout.svelte
 <nav>
 	<a href="/">Home</a>
 	<a href="/about">About</a>
 	<a href="/settings">Settings</a>
 </nav>
 
-<slot></slot>
+{@render children()}
 ```
 
 If we create pages for `/`, `/about` and `/settings`...
@@ -196,8 +209,8 @@ We can create a layout that only applies to pages below `/settings` (while inher
 ```svelte
 <!--- file: src/routes/settings/+layout.svelte --->
 <script>
-	/** @type {import('./$types').LayoutData} */
-	export let data;
+	/** @type {{ data: import('./$types').LayoutData, children: import('svelte').Snippet }} */
+	let { data, children } = $props();
 </script>
 
 <h1>Settings</h1>
@@ -208,7 +221,7 @@ We can create a layout that only applies to pages below `/settings` (while inher
 	{/each}
 </div>
 
-<slot></slot>
+{@render children()}
 ```
 
 You can see how `data` is populated by looking at the `+layout.js` example in the next section just below.
@@ -239,8 +252,8 @@ Data returned from a layout's `load` function is also available to all its child
 ```svelte
 <!--- file: src/routes/settings/profile/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 
 	console.log(data.sections); // [{ slug: 'profile', title: 'Profile' }, ...]
 </script>
@@ -370,13 +383,13 @@ export async function fallback({ request }) {
 
 Throughout the examples above, we've been importing types from a `$types.d.ts` file. This is a file SvelteKit creates for you in a hidden directory if you're using TypeScript (or JavaScript with JSDoc type annotations) to give you type safety when working with your root files.
 
-For example, annotating `export let data` with `PageData` (or `LayoutData`, for a `+layout.svelte` file) tells TypeScript that the type of `data` is whatever was returned from `load`:
+For example, annotating `let { data } = $props()` with `PageData` (or `LayoutData`, for a `+layout.svelte` file) tells TypeScript that the type of `data` is whatever was returned from `load`:
 
 ```svelte
 <!--- file: src/routes/blog/[slug]/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 </script>
 ```
 

documentation/docs/20-core-concepts/20-load.md

@@ -24,14 +24,17 @@ export function load({ params }) {
 ```svelte
 <!--- file: src/routes/blog/[slug]/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 </script>
 
 <h1>{data.post.title}</h1>
 <div>{@html data.post.content}</div>
 ```
 
+> [!LEGACY] In Svelte 4
+> In Svelte 4, you'd use `export let data` instead
+
 Thanks to the generated `$types` module, we get full type safety.
 
 A `load` function in a `+page.js` file runs both on the server and in the browser (unless combined with `export const ssr = false`, in which case it will [only run in the browser](page-options#ssr)). If your `load` function should _always_ run on the server (because it uses private environment variables, for example, or accesses a database) then it would go in a `+page.server.js` instead.
@@ -85,13 +88,13 @@ export async function load() {
 ```svelte
 <!--- file: src/routes/blog/[slug]/+layout.svelte --->
 <script>
-	/** @type {import('./$types').LayoutData} */
-	export let data;
+	/** @type {{ data: import('./$types').LayoutData, children: Snippet }} */
+	let { data, children } = $props();
 </script>
 
 <main>
-	<!-- +page.svelte is rendered in this <slot> -->
-	<slot />
+	<!-- +page.svelte is `@render`ed here -->
+	{@render children()}
 </main>
 
 <aside>
@@ -115,13 +118,13 @@ Data returned from layout `load` functions is available to child `+layout.svelte
 <script>
 	+++import { page } from '$app/stores';+++
 
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 
 +++	// we can access `data.posts` because it's returned from
 	// the parent layout `load` function
 	let index = $derived(data.posts.findIndex(post => post.slug === $page.params.slug));
-	let next = $derived(data.posts[index - 1];)+++
+	let next = $derived(data.posts[index + 1]);+++
 </script>
 
 <h1>{data.post.title}</h1>
@@ -365,8 +368,8 @@ export async function load({ parent }) {
 ```svelte
 <!--- file: src/routes/abc/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 </script>
 
 <!-- renders `1 + 2 = 3` -->
@@ -504,8 +507,8 @@ This is useful for creating skeleton loading states, for example:
 ```svelte
 <!--- file: src/routes/blog/[slug]/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 </script>
 
 <h1>{data.post.title}</h1>
@@ -645,8 +648,8 @@ export async function load({ fetch, depends }) {
 <script>
 	import { invalidate, invalidateAll } from '$app/navigation';
 
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 
 	function rerunLoadFunction() {
 		// any of these will cause the `load` function to rerun

documentation/docs/20-core-concepts/30-form-actions.md

@@ -140,11 +140,8 @@ export const actions = {
 ```svelte
 <!--- file: src/routes/login/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
-
-	/** @type {import('./$types').ActionData} */
-	export let form;
+	/** @type {{ data: import('./$types').PageData, form: import('./$types').ActionData }} */
+	let { data, form } = $props();
 </script>
 
 {#if form?.success}
@@ -154,6 +151,9 @@ export const actions = {
 {/if}
 ```
 
+> [!LEGACY] In Svelte 4
+> In Svelte 4, you'd use `export let data` and `export let form` instead to declare properties
+
 ### Validation errors
 
 If the request couldn't be processed because of invalid data, you can return validation errors — along with the previously submitted form values — back to the user so that they can try again. The `fail` function lets you return an HTTP status code (typically 400 or 422, in the case of validation errors) along with the data. The status code is available through `$page.status` and the data through `form`:
@@ -339,8 +339,8 @@ The easiest way to progressively enhance a form is to add the `use:enhance` acti
 <script>
 	+++import { enhance } from '$app/forms';+++
 
-	/** @type {import('./$types').ActionData} */
-	export let form;
+	/** @type {{ form: import('./$types').ActionData }} */
+	let { form } = $props();
 </script>
 
 <form method="POST" +++use:enhance+++>
@@ -390,8 +390,8 @@ If you return a callback, you may need to reproduce part of the default `use:enh
 <script>
 	import { enhance, +++applyAction+++ } from '$app/forms';
 
-	/** @type {import('./$types').ActionData} */
-	export let form;
+	/** @type {{ form: import('./$types').ActionData }} */
+	let { form } = $props();
 </script>
 
 <form
@@ -427,11 +427,8 @@ We can also implement progressive enhancement ourselves, without `use:enhance`,
 	import { invalidateAll, goto } from '$app/navigation';
 	import { applyAction, deserialize } from '$app/forms';
 
-	/** @type {import('./$types').ActionData} */
-	export let form;
-
-	/** @type {any} */
-	let error;
+	/** @type {{ form: import('./$types').ActionData }} */
+	let { form } = $props();
 
 	/** @param {{ currentTarget: EventTarget & HTMLFormElement}} event */
 	async function handleSubmit(event) {

documentation/docs/20-core-concepts/50-state-management.md

@@ -90,12 +90,14 @@ You might wonder how we're able to use `$page.data` and other [app stores]($app-
 	import { setContext } from 'svelte';
 	import { writable } from 'svelte/store';
 
-	/** @type {import('./$types').LayoutData} */
-	export let data;
+	/** @type {{ data: import('./$types').LayoutData }} */
+	let { data } = $props();
 
 	// Create a store and update it when necessary...
-	const user = writable();
-	$: user.set(data.user);
+	const user = writable(data.user);
+	$effect.pre(() => {
+		user.set(data.user);
+	});
 
 	// ...and add it to the context for child components to access
 	setContext('user', user);
@@ -125,8 +127,8 @@ When you navigate around your application, SvelteKit reuses existing layout and
 ```svelte
 <!--- file: src/routes/blog/[slug]/+page.svelte --->
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 
 	// THIS CODE IS BUGGY!
 	const wordCount = data.content.split(' ').length;
@@ -148,8 +150,8 @@ Instead, we need to make the value [_reactive_](/tutorial/svelte/state):
 ```svelte
 /// file: src/routes/blog/[slug]/+page.svelte
 <script>
-	/** @type {import('./$types').PageData} */
-	export let data;
+	/** @type {{ data: import('./$types').PageData }} */
+	let { data } = $props();
 
 +++	let wordCount = $state(data.content.split(' ').length);
 	let estimatedReadingTime = $derived(wordCount / 250);+++

documentation/docs/25-build-and-deploy/90-adapter-vercel.md

@@ -140,8 +140,8 @@ export function load() {
 ```svelte
 <!--- file: +layout.svelte --->
 <script>
-	/** @type {import('./$types').LayoutServerData} */
-	export let data;
+	/** @type {{ data: import('./$types').LayoutServerData }} */
+	let { data } = $props();
 </script>
 
 <p>This staging environment was deployed from {data.deploymentGitBranch}.</p>

documentation/docs/30-advanced/10-advanced-routing.md

@@ -193,7 +193,7 @@ You can also put a `+page` directly inside a `(group)`, for example if `/` shoul
 
 ### Breaking out of layouts
 
-The root layout applies to every page of your app — if omitted, it defaults to `<slot />`. If you want some pages to have a different layout hierarchy than the rest, then you can put your entire app inside one or more groups _except_ the routes that should not inherit the common layouts.
+The root layout applies to every page of your app — if omitted, it defaults to `{@render children()}`. If you want some pages to have a different layout hierarchy than the rest, then you can put your entire app inside one or more groups _except_ the routes that should not inherit the common layouts.
 
 In the example above, the `/admin` route does not inherit either the `(app)` or `(marketing)` layouts.
 
@@ -260,11 +260,11 @@ Not all use cases are suited for layout grouping, nor should you feel compelled
 <!--- file: src/routes/nested/route/[email protected] --->
 <script>
 	import ReusableLayout from '$lib/ReusableLayout.svelte';
-	export let data;
+	let { data, children } = $props();
 </script>
 
 <ReusableLayout {data}>
-	<slot />
+	{@render children()}
 </ReusableLayout>
 ```
 

documentation/docs/30-advanced/65-snapshots.md

@@ -11,7 +11,7 @@ To do this, export a `snapshot` object with `capture` and `restore` methods from
 ```svelte
 <!--- file: +page.svelte --->
 <script>
-	let comment = '';
+	let comment = $state('');
 
 	/** @type {import('./$types').Snapshot<string>} */
 	export const snapshot = {

documentation/docs/30-advanced/67-shallow-routing.md

@@ -51,7 +51,7 @@ For this to work, you need to load the data that the `+page.svelte` expects. A c
 	import Modal from './Modal.svelte';
 	import PhotoPage from './[id]/+page.svelte';
 
-	export let data;
+	let { data } = $props();
 </script>
 
 {#each data.thumbnails as thumbnail}

documentation/docs/98-reference/26-$lib.md

@@ -2,4 +2,18 @@
 title: $lib
 ---
 
-TODO
+SvelteKit automatically makes files under `src/lib` available using the `$lib` import alias. You can change which directory this alias points to in your [config file](configuration#files).
+
+```svelte
+<!--- file: src/lib/Component.svelte --->
+A reusable component
+```
+
+```svelte
+<!--- file: src/routes/+page.svelte --->
+<script>
+    import Component from '$lib/Component.svelte';
+</script>
+
+<Component />
+```