sync svelte docs

Author: svelte-docs-bot[bot]

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

@@ -270,11 +270,11 @@ 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#H4sIAAAAAAAACpVRy26DMBD8FcvKgUhtoIdeHBwp31F6MGSJkBbHwksEQvx77aWQqooq9bgzOzP7mGTdIHipPiZJowOpGJAv0po2VmfnDv4OSBErjYdneHWzBJaCjcx91TWOToUtCIEE3cig0OIty44r5l1oDtjOkyFIsv3GINQ_CNYyGegd1DVUlCR7oU9iilDUcP8S8roYs9n8p2wdYNVFm4csTx872BxNCcjr5I11fdgonEkXsjP2CoUUZWMv6m6wBz2x7yxaM-iJvWeRsvSbSVeUy5i0uf8vKA78NIeJLSZWv1I8jQjLdyK4XuTSeIdmVKJGGI4LdjVOiezwDu1yG74My8PLCQaSiroe5s_5C2PHrkVGAgAA)):
+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)):
 
 ```svelte
 <script>
-	let total = 100;
+	const total = 100;
 	let spent = $state(0);
 	let left = $state(total);
 
@@ -298,32 +298,26 @@ You might be tempted to do something convoluted with effects to link one value t
 </label>
 ```
 
-Instead, use `oninput` callbacks or — better still — [function bindings](bind#Function-bindings) where possible ([demo](/playground/untitled#H4sIAAAAAAAAE51SsW6DMBT8FcvqABINdOhCIFKXTt06lg4GHpElYyz8iECIf69tcIIipo6-u3f3fPZMJWuBpvRzkBXyTpKSy5rLq6YRbbgATdOfmeKkrMgCBt9GPpQ66RsItFjJNBzhVScRJBobmumq5wovhSxQABLskAmSk7ckOXtMKyM22ItGhhAk4Z0R0OwIN-tIQzd-90HVhvy2HsGNiQFCMltBgd7XoecV2xzXNV7XaEcth7ZfRv7kujnsTX2Qd7USb5rFjwZkJlgJwpWRcakG04cpOS9oz-QVCuoeInXW-RyEJL-sG0b7Wy6kZWM-u7CFxM5tdrIl9qg72vB74H-y7T2iXROHyVb0CLanp1yNk4D1A1jQ91hzrQSbUtIIGLcir0ylJDm9Q7urz42bX4UwIk2xH2D5Xf4A7SeMcMQCAAA=)):
+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=)):
 
 ```svelte
 <script>
-	let total = 100;
+	const total = 100;
 	let spent = $state(0);
-	let left = $state(total);
-
-	function updateSpent(value) {
-		spent = value;
-		left = total - spent;
-	}
+	let left = $derived(total - spent);
 
-	function updateLeft(value) {
-		left = value;
++++	function updateLeft(left) {
 		spent = total - left;
-	}
+	}+++
 </script>
 
 <label>
-	<input type="range" bind:value={() => spent, updateSpent} max={total} />
+	<input type="range" bind:value={spent} max={total} />
 	{spent}/{total} spent
 </label>
 
 <label>
-	<input type="range" bind:value={() => left, updateLeft} max={total} />
+	<input type="range" +++bind:value={() => left, updateLeft}+++ max={total} />
 	{left}/{total} left
 </label>
 ```

apps/svelte.dev/content/docs/svelte/03-template-syntax/12-bind.md

@@ -5,7 +5,7 @@ title: bind:
 
 Data ordinarily flows down, from parent to child. The `bind:` directive allows data to flow the other way, from child to parent.
 
-The general syntax is `bind:property={expression}`, where `expression` is an _lvalue_ (i.e. a variable or an object property). When the expression is an identifier with the same name as the property, we can omit the expression — in other words these are equivalent:
+The general syntax is `bind:property={expression}`, where `expression` is an [_lvalue_](https://press.rebus.community/programmingfundamentals/chapter/lvalue-and-rvalue/) (i.e. a variable or an object property). When the expression is an identifier with the same name as the property, we can omit the expression — in other words these are equivalent:
 
 <!-- prettier-ignore -->
 ```svelte

apps/svelte.dev/content/docs/svelte/07-misc/04-custom-elements.md

@@ -115,6 +115,8 @@ When constructing a custom element, you can tailor several aspects by defining `
 ...
 ```
 
+> [!NOTE] While Typescript is supported in the `extend` function, it is subject to limitations: you need to set `lang="ts"` on one of the scripts AND you can only use [erasable syntax](https://www.typescriptlang.org/tsconfig/#erasableSyntaxOnly) in it. They are not processed by script preprocessors.
+
 ## Caveats and limitations
 
 Custom elements can be a useful way to package components for consumption in a non-Svelte app, as they will work with vanilla HTML and JavaScript as well as [most frameworks](https://custom-elements-everywhere.com/). There are, however, some important differences to be aware of: