Sync svelte docs (#1891)

sync svelte docs

Co-authored-by: svelte-docs-bot[bot] <196124396+svelte-docs-bot[bot]@users.noreply.github.com>

Author: github-actions[bot]

apps/svelte.dev/content/docs/svelte/02-runes/04-$effect.md

@@ -42,9 +42,11 @@ You can use `$effect` anywhere, not just at the top level of a component, as lon
 
 > [!NOTE] Svelte uses effects internally to represent logic and expressions in your template — this is how `<h1>hello {name}!</h1>` updates when `name` changes.
 
-An effect can return a _teardown function_ which will run immediately before the effect re-runs ([demo](/playground/untitled#H4sIAAAAAAAAE42SQVODMBCF_8pOxkPRKq3HCsx49K4n64xpskjGkDDJ0tph-O8uINo6HjxB3u7HvrehE07WKDbiyZEhi1osRWksRrF57gQdm6E2CKx_dd43zU3co6VB28mIf-nKO0JH_BmRRRVMQ8XWbXkAgfKtI8jhIpIkXKySu7lSG2tNRGZ1_GlYr1ZTD3ddYFmiosUigbyAbpC2lKbwWJkIB8ZhhxBQBWRSw6FCh3sM8GrYTthL-wqqku4N44TyqEgwF3lmRHr4Op0PGXoH31c5rO8mqV-eOZ49bikgtcHBL55tmhIkEMqg_cFB2TpFxjtg703we6NRL8HQFCS07oSUCZi6Rm04lz1yytIHBKoQpo1w6Gsm4gmyS8b8Y5PydeMdX8gwS2Ok4I-ov5NZtvQde95GMsccn_1wzNKfu3RZtS66cSl9lvL7qO1aIk7knbJGvefdtIOzi73M4bYvovUHDFk6AcX_0HRESxnpBOW_jfCDxIZCi_1L_wm4xGQ60wIAAA==)).
+An effect can return a _teardown function_ which will run immediately before the effect re-runs:
 
+<!-- codeblock:start {"title":"Effect teardown"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	let count = $state(0);
 	let milliseconds = $state(1000);
@@ -69,6 +71,7 @@ An effect can return a _teardown function_ which will run immediately before the
 <button onclick={() => (milliseconds *= 2)}>slower</button>
 <button onclick={() => (milliseconds /= 2)}>faster</button>
 ```
+<!-- codeblock:end -->
 
 Teardown functions also run when the effect is destroyed, which happens when its parent is destroyed (for example, a component is unmounted) or the parent effect re-runs.
 
@@ -207,9 +210,11 @@ Apart from the timing, `$effect.pre` works exactly like `$effect`.
 
 ## `$effect.tracking`
 
-The `$effect.tracking` rune is an advanced feature that tells you whether or not the code is running inside a tracking context, such as an effect or inside your template ([demo](/playground/untitled#H4sIAAAAAAAACn3PwYrCMBDG8VeZDYIt2PYeY8Dn2HrIhqkU08nQjItS-u6buAt7UDzmz8ePyaKGMWBS-nNRcmdU-hHUTpGbyuvI3KZvDFLal0v4qvtIgiSZUSb5eWSxPfWSc4oB2xDP1XYk8HHiSHkICeXKeruDDQ4Demlldv4y0rmq6z10HQwuJMxGVv4mVVXDwcJS0jP9u3knynwtoKz1vifT_Z9Jhm0WBCcOTlDD8kyspmML5qNpHg40jc3fFryJ0iWsp_UHgz3180oBAAA=)):
+The `$effect.tracking` rune is an advanced feature that tells you whether or not the code is running inside a tracking context, such as an effect or inside your template:
 
+<!-- codeblock:start {"title":"$effect.tracking()"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	console.log('in component setup:', $effect.tracking()); // false
 
@@ -220,14 +225,27 @@ The `$effect.tracking` rune is an advanced feature that tells you whether or not
 
 <p>in template: {$effect.tracking()}</p> <!-- true -->
 ```
+<!-- codeblock:end -->
 
 It is used to implement abstractions like [`createSubscriber`](/docs/svelte/svelte-reactivity#createSubscriber), which will create listeners to update reactive values but _only_ if those values are being tracked (rather than, for example, read inside an event handler).
 
 ## `$effect.pending`
 
-When using [`await`](await-expressions) in components, the `$effect.pending()` rune tells you how many promises are pending in the current [boundary](svelte-boundary), not including child boundaries ([demo](/playground/untitled#H4sIAAAAAAAAE3WRMU_DMBCF_8rJdHDUqilILGkaiY2RgY0yOPYZWbiOFV8IleX_jpMUEAIWS_7u-d27c2ROnJBV7B6t7WDsequAozKEqmAbpo3FwKqnyOjsJ90EMr-8uvN-G97Q0sRaEfAvLjtH6CjbsDrI3nhqju5IFgkEHGAVSBDy62L_SdtvejPTzEU4Owl6cJJM50AoxcUG2gLiVM31URgChyM89N3JBORcF3BoICA9mhN2A3G9gdvdrij2UJYgejLaSCMsKLTivNj0SEOf7WEN7ZwnHV1dfqd2dTsQ5QCdk9bI10PkcxexXqcmH3W51Jt_le2kbH8os9Y3UaTcNLYpDx-Xab6GTHXpZ128MhpWqDVK2np0yrgXXqQpaLa4APDLBkIF8bd2sYql0Sn_DeE7sYr6AdNzvgljR-MUq7SwAdMHeUtgHR4CAAA=)):
+When using [`await`](await-expressions) in components, the `$effect.pending()` rune tells you how many promises are pending in the current [boundary](svelte-boundary), not including child boundaries:
 
+<!-- codeblock:start {"title":"$effect.pending"} -->
 ```svelte
+<!--- file: App.svelte --->
+<script>
+	let a = $state(1);
+	let b = $state(2);
+
+	async function add(a, b) {
+		await new Promise((f) => setTimeout(f, 500)); // artificial delay
+		return a + b;
+	}
+</script>
+
 <button onclick={() => a++}>a++</button>
 <button onclick={() => b++}>b++</button>
 
@@ -237,6 +255,7 @@ When using [`await`](await-expressions) in components, the `$effect.pending()` r
 	<p>pending promises: {$effect.pending()}</p>
 {/if}
 ```
+<!-- codeblock:end -->
 
 ## `$effect.root`
 
@@ -286,9 +305,11 @@ In general, `$effect` is best considered something of an escape hatch — useful
 
 If you're using an effect because you want to be able to reassign the derived value (to build an optimistic UI, for example) note that [deriveds can be directly overridden]($derived#Overriding-derived-values) as of Svelte 5.25.
 
-You might be tempted to do something convoluted with effects to link one value to another. The following example shows two inputs for "money spent" and "money left" that are connected to each other. If you update one, the other should update accordingly. Don't use effects for this ([demo](/playground/untitled#H4sIAAAAAAAAE5WRTWrDMBCFryKGLBJoY3fRjWIHeoiu6i6UZBwEY0VE49TB-O6VxrFTSih0qe_Ne_OjHpxpEDS8O7ZMeIAnqC1hAP3RA1990hKI_Fb55v06XJA4sZ0J-IjvT47RcYyBIuzP1vO2chVHHFjxiQ2pUr3k-SZRQlbBx_LIFoEN4zJfzQph_UMQr4hRXmBd456Xy5Uqt6pPKHmkfmzyPAZL2PCnbRpg8qWYu63I7lu4gswOSRYqrPNt3CgeqqzgbNwRK1A76w76YqjFspfcQTWmK3vJHlQm1puSTVSeqdOc_r9GaeCHfUSY26TXry6Br4RSK3C6yMEGT-aqVU3YbUZ2NF6rfP2KzXgbuYzY46czdgyazy0On_FlLH3F-UDXhgIO35UGlA1rAgAA)):
+You might be tempted to do something convoluted with effects to link one value to another. The following example shows two inputs for "money spent" and "money left" that are connected to each other. If you update one, the other should update accordingly. Instead of using effects for this...
 
+<!-- codeblock:start {"title":"Setting state in effects (don't do this!)"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	const total = 100;
 	let spent = $state(0);
@@ -312,11 +333,21 @@ You might be tempted to do something convoluted with effects to link one value t
 	<input type="range" bind:value={left} max={total} />
 	{left}/{total} left
 </label>
+
+<style>
+	label {
+		display: flex;
+		gap: 0.5em;
+	}
+</style>
 ```
+<!-- codeblock:end -->
 
-Instead, use `oninput` callbacks or — better still — [function bindings](bind#Function-bindings) where possible ([demo](/playground/untitled#H4sIAAAAAAAAE5VRvW7CMBB-FcvqECQK6dDFJEgsnfoGTQdDLsjSxVjxhYKivHvPBwFUsXS8774_nwftbQva6I_e78gdvNo6Xzu_j3quG4cQtfkaNJ1DIiWA8atkE8IiHgEpYVsb4Rm-O3gCT2yji7jrXKB15StiOJKiA1lUpXrL81VCEUjFwHTGXiJZgiyf3TYIjSxq6NwR6uyifr0ohMbEZnpHH2rWf7ImS8KZGtK6osl_UqelRIyVL5b3ir5AuwWUtoXzoee6fIWy0p31e6i0XMocLfZQDuI6qtaeykGcR7UU6XWznFAZU9LN_X9B2UyVayk9f3ji0-REugen6U9upDOCcAWcLlS7GNCejWoQTqsLtrfBqHzxDu3DrUTOf0xwIm2o62H85sk6_OHG2jQWI4y_3byXXGMCAAA=)):
+...use `oninput` callbacks or — better still — [function bindings](bind#Function-bindings) where possible:
 
+<!-- codeblock:start {"title":"Setting state with function bindings"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	const total = 100;
 	let spent = $state(0);
@@ -336,6 +367,14 @@ Instead, use `oninput` callbacks or — better still — [function bindings](bin
 	<input type="range" +++bind:value={() => left, updateLeft}+++ max={total} />
 	{left}/{total} left
 </label>
+
+<style>
+	label {
+		display: flex;
+		gap: 0.5em;
+	}
+</style>
 ```
+<!-- codeblock:end -->
 
 If you absolutely have to update `$state` within an effect and run into an infinite loop because you read and write to the same `$state`, use [untrack](svelte#untrack).

apps/svelte.dev/content/docs/svelte/02-runes/05-$props.md

@@ -65,8 +65,9 @@ let { a, b, c, ...others } = $props();
 
 ## Updating props
 
-References to a prop inside a component update when the prop itself updates — when `count` changes in `App.svelte`, it will also change inside `Child.svelte`. But the child component is able to temporarily override the prop value, which can be useful for unsaved ephemeral state ([demo](/playground/untitled#H4sIAAAAAAAAE6WQ0WrDMAxFf0WIQR0Wmu3VTQJln7HsIfVcZubIxlbGRvC_DzuBraN92qPula50tODZWB1RPi_IX16jLALWSOOUq6P3-_ihLWftNEZ9TVeOWBNHlNhGFYznfqCBzeRdYHh6M_YVzsFNsNs3pdpGd4eBcqPVDMrNxNDBXeSRtXioDgO1zU8ataeZ2RE4Utao924RFXQ9iHXwvoPHKpW1xY4g_Bg0cSVhKS0p560Za95612ZC02ONrD8ZJYdZp_rGQ37ff_mSP86Np2TWZaNNmdcH56P4P67K66_SXoK9pG-5dF5Z9QEAAA==)):
+References to a prop inside a component update when the prop itself updates — when `count` changes in `App.svelte`, it will also change inside `Child.svelte`. But the child component is able to temporarily override the prop value, which can be useful for unsaved ephemeral state:
 
+<!-- codeblock:start {"title":"Temporarily updating props","selected":"Child.svelte"} -->
 ```svelte
 <!--- file: App.svelte --->
 <script>
@@ -92,11 +93,13 @@ References to a prop inside a component update when the prop itself updates —
 	clicks (child): {count}
 </button>
 ```
+<!-- codeblock:end -->
 
 While you can temporarily _reassign_ props, you should not _mutate_ props unless they are [bindable]($bindable).
 
-If the prop is a regular object, the mutation will have no effect ([demo](/playground/untitled#H4sIAAAAAAAAE3WQwU7DMBBEf2W1QmorQgJXk0RC3PkBwiExG9WQrC17U4Es_ztKUkQp9OjxzM7bjcjtSKjwyfKNp1aLORA4b13ADHszUED1HFE-3eyaBcy-Mw_O5eFAg8xa1wb6T9eWhVgCKiyD9sZJ3XAjZnTWCzzuzfAKvbcjbPJieR2jm_uGy-InweXqtd0baaliBG0nFgW3kBIUNWYo9CGoxE-UsgvIpw2_oc9-LmAPJBCPDJCggqvlVtvdH9puErEMlvVg9HsVtzuoaojzkKKAfRuALVDfk5ZZW0fmy05wXcFdwyktlUs-KIinljTXrRVnm7-kL9dYLVbUAQAA)):
+If the prop is a regular object, the mutation will have no effect:
 
+<!-- codeblock:start {"title":"Non-reactive props","selected":"Child.svelte"} -->
 ```svelte
 <!--- file: App.svelte --->
 <script>
@@ -119,9 +122,11 @@ If the prop is a regular object, the mutation will have no effect ([demo](/playg
 	clicks: {object.count}
 </button>
 ```
+<!-- codeblock:end -->
 
-If the prop is a reactive state proxy, however, then mutations _will_ have an effect but you will see an [`ownership_invalid_mutation`](runtime-warnings#Client-warnings-ownership_invalid_mutation) warning, because the component is mutating state that does not 'belong' to it ([demo](/playground/untitled#H4sIAAAAAAAAE3WR0U7DMAxFf8VESBuiauG1WycheOEbKA9p67FA6kSNszJV-XeUZhMw2GN8r-1znUmQ7FGU4pn2UqsOes-SlSGRia3S6ET5Mgk-2OiJBZGdOh6szd0eNcdaIx3-V28NMRI7UYq1awdleVNTzaq3ZmB43CndwXYwPSzyYn4dWxermqJRI4Np3rFlqODasWRcTtAaT1zCHYSbVU3r4nsyrdPMKTUFKDYiE4yfLEoePIbsQpqfy3_nOVMuJIqg0wk1RFg7GOuWfwEbz2wIDLVatR_VtLyBagNTHFIUMCqtoZXeIfAOU1JoUJsR2IC3nWTMjt7GM4yKdyBhlAMpesvhydCC0y_i0ZagHByMh26WzUhXUUxKnpbcVnBfUwhznJnNlac7JkuIURL-2VVfwxflyrWcSQIAAA==)):
+If the prop is a reactive state proxy, however, then mutations _will_ have an effect but you will see an [`ownership_invalid_mutation`](runtime-warnings#Client-warnings-ownership_invalid_mutation) warning, because the component is mutating state that does not 'belong' to it:
 
+<!-- codeblock:start {"title":"Invalid mutation","selected":"Child.svelte"} -->
 ```svelte
 <!--- file: App.svelte --->
 <script>
@@ -148,8 +153,19 @@ If the prop is a reactive state proxy, however, then mutations _will_ have an ef
 	clicks: {object.count}
 </button>
 ```
+<!-- codeblock:end -->
 
-The fallback value of a prop not declared with `$bindable` is left untouched — it is not turned into a reactive state proxy — meaning mutations will not cause updates ([demo](/playground/untitled#H4sIAAAAAAAAE3WQwU7DMBBEf2VkIbUVoYFraCIh7vwA4eC4G9Wta1vxpgJZ_nfkBEQp9OjxzOzTRGHlkUQlXpy9G0gq1idCL43ppDrAD84HUYheGwqieo2CP3y2Z0EU3-En79fhRIaz1slA_-nKWSbLQVRiE9SgPTetbVkfvRsYzztttugHd8RiXU6vr-jisbWb8idhN7O3bEQhmN5ZVDyMlIorcOddv_Eufq4AGmJEuG5PilEjQrnRcoV7JCTUuJlGWq7-YHYjs7NwVhmtDnVcrlA3iLmzLLGTAdaB-j736h68Oxv-JM1I0AFjoG1OzPfX023c1nhobUoT39QeKsRzS8owM8DFTG_pE6dcVl70AQAA))
+The fallback value of a prop not declared with `$bindable` is left untouched — it is not turned into a reactive state proxy — meaning mutations will not cause updates:
+
+<!-- codeblock:start {"title":"Non-reactive fallback props","selected":"Child.svelte"} -->
+```svelte
+<!--- file: App.svelte --->
+<script>
+	import Child from './Child.svelte';
+</script>
+
+<Child />
+```
 
 ```svelte
 <!--- file: Child.svelte --->
@@ -164,6 +180,7 @@ The fallback value of a prop not declared with `$bindable` is left untouched —
 	clicks: {object.count}
 </button>
 ```
+<!-- codeblock:end -->
 
 In summary: don't mutate props. Either use callback props to communicate changes, or — if parent and child should share the same object — use the [`$bindable`]($bindable) rune.
 

apps/svelte.dev/content/docs/svelte/02-runes/07-$inspect.md

@@ -6,9 +6,11 @@ tags: rune-inspect
 
 > [!NOTE] `$inspect` only works during development. In a production build it becomes a noop.
 
-The `$inspect` rune is roughly equivalent to `console.log`, with the exception that it will re-run whenever its argument changes. `$inspect` tracks reactive state deeply, meaning that updating something inside an object or array using fine-grained reactivity will cause it to re-fire ([demo](/playground/untitled#H4sIAAAAAAAACkWQ0YqDQAxFfyUMhSotdZ-tCvu431AXtGOqQ2NmmMm0LOK_r7Utfby5JzeXTOpiCIPKT5PidkSVq2_n1F7Jn3uIcEMSXHSw0evHpAjaGydVzbUQCmgbWaCETZBWMPlKj29nxBDaHj_edkAiu12JhdkYDg61JGvE_s2nR8gyuBuiJZuDJTyQ7eE-IEOzog1YD80Lb0APLfdYc5F9qnFxjiKWwbImo6_llKRQVs-2u91c_bD2OCJLkT3JZasw7KLA2XCX31qKWE6vIzNk1fKE0XbmYrBTufiI8-_8D2cUWBA_AQAA)):
+The `$inspect` rune is roughly equivalent to `console.log`, with the exception that it will re-run whenever its argument changes. `$inspect` tracks reactive state deeply, meaning that updating something inside an object or array using fine-grained reactivity will cause it to re-fire:
 
+<!-- codeblock:start {"title":"$inspect(...)"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	let count = $state(0);
 	let message = $state('hello');
@@ -19,14 +21,17 @@ The `$inspect` rune is roughly equivalent to `console.log`, with the exception t
 <button onclick={() => count++}>Increment</button>
 <input bind:value={message} />
 ```
+<!-- codeblock:end -->
 
 On updates, a stack trace will be printed, making it easy to find the origin of a state change (unless you're in the playground, due to technical limitations).
 
 ## $inspect(...).with
 
-`$inspect` returns a property `with`, which you can invoke with a callback, which will then be invoked instead of `console.log`. The first argument to the callback is either `"init"` or `"update"`; subsequent arguments are the values passed to `$inspect` ([demo](/playground/untitled#H4sIAAAAAAAACkVQ24qDMBD9lSEUqlTqPlsj7ON-w7pQG8c2VCchmVSK-O-bKMs-DefKYRYx6BG9qL4XQd2EohKf1opC8Nsm4F84MkbsTXAqMbVXTltuWmp5RAZlAjFIOHjuGLOP_BKVqB00eYuKs82Qn2fNjyxLtcWeyUE2sCRry3qATQIpJRyD7WPVMf9TW-7xFu53dBcoSzAOrsqQNyOe2XUKr0Xi5kcMvdDB2wSYO-I9vKazplV1-T-d6ltgNgSG1KjVUy7ZtmdbdjqtzRcphxMS1-XubOITJtPrQWMvKnYB15_1F7KKadA_AQAA)):
+`$inspect(...)` returns an object with a `with` method, which you can invoke with a callback that will then be invoked instead of `console.log`. The first argument to the callback is either `"init"` or `"update"`; subsequent arguments are the values passed to `$inspect`:
 
+<!-- codeblock:start {"title":"$inspect(...).with(...)"} -->
 ```svelte
+<!--- file: App.svelte --->
 <script>
 	let count = $state(0);
 
@@ -39,6 +44,7 @@ On updates, a stack trace will be printed, making it easy to find the origin of
 
 <button onclick={() => count++}>Increment</button>
 ```
+<!-- codeblock:end -->
 
 ## $inspect.trace(...)
 

apps/svelte.dev/content/docs/svelte/03-template-syntax/03-each.md

@@ -90,17 +90,34 @@ You can freely use destructuring and rest patterns in each blocks.
 {#each expression, index}...{/each}
 ```
 
-In case you just want to render something `n` times, you can omit the `as` part ([demo](/playground/untitled#H4sIAAAAAAAAE3WR0W7CMAxFf8XKNAk0WsSeUEaRpn3Guoc0MbQiJFHiMlDVf18SOrZJ48259_jaVgZmxBEZZ28thgCNFV6xBdt1GgPj7wOji0t2EqI-wa_OleGEmpLWiID_6dIaQkMxhm1UdwKpRQhVzWSaVORJNdvWpqbhAYVsYQCNZk8thzWMC_DCHMZk3wPSThNQ088I3mghD9UwSwHwlLE5PMIzVFUFq3G7WUZ2OyUvU3JOuZU332wCXTRmtPy1NgzXZtUFp8WFw9536uWqpbIgPEaDsJBW90cTOHh0KGi2XsBq5-cT6-3nPauxXqHnsHJnCFZ3CvJVkyuCQ0mFF9TZyCQ162WGvteLKfG197Y3iv_pz_fmS68Hxt8iPBPj5HscP8YvCNX7uhYCAAA=)):
+In case you just want to render something `n` times, you can omit the `as` part:
 
+<!-- codeblock:start {"title":"Chess board"} -->
 ```svelte
+<!--- file: App.svelte --->
 <div class="chess-board">
 	{#each { length: 8 }, rank}
 		{#each { length: 8 }, file}
 			<div class:black={(rank + file) % 2 === 1}></div>
 		{/each}
 	{/each}
 </div>
+
+<style>
+	.chess-board {
+		display: grid;
+		grid-template-columns: repeat(8, 1fr);
+		rows: repeat(8, 1fr);
+		border: 1px solid black;
+		aspect-ratio: 1;
+
+		.black {
+			background: black;
+		}
+	}
+</style>
 ```
+<!-- codeblock:end -->
 
 ## Else blocks