Svelte 5 .cursorrules Cursor AI Prompt File Examples

NEW

Svelte 5 SvelteKit 2 .cursorrules prompt file

I'm using svelte 5 instead of svelte 4 here is an overview of the changes.

Overview

Svelte 5 introduces runes, a set of advanced primitives for controlling reactivity. The runes replace certain non-runes features and provide more explicit control over state and effects.

$state

Purpose: Declare reactive state.
Usage:

`<script>`let count = $state(0);`</script>`

Replaces: Top-level let declarations in non-runes mode.
Class Fields:

class Todo {	done = $state(false);	text = $state();	constructor(text) {		this.text = text;	}}

Deep Reactivity: Only plain objects and arrays become deeply reactive.

$state.raw

Purpose: Declare state that cannot be mutated, only reassigned.
Usage:

`<script>`let numbers = $state.raw([1, 2, 3]);`</script>`

Performance: Improves with large arrays and objects.

$state.snapshot

Purpose: Take a static snapshot of $state.
Usage:

`<script>`	let counter = $state({ count: 0 });	function onClick() {		console.log($state.snapshot(counter));	}`</script>`

$derived

Purpose: Declare derived state.
Usage:

`<script>`let count = $state(0); let doubled = $derived(count * 2);`</script>`

Replaces: Reactive variables computed using $: in non-runes mode.

$derived.by

Purpose: Create complex derivations with a function.
Usage:

`<script>`	let numbers = $state([1, 2, 3]); let total = $derived.by(() => numbers.reduce((a, b) => a + b,	0));`</script>`

$effect

Purpose: Run side-effects when values change.
Usage:

`<script>`	let size = $state(50);	let color = $state('#ff3e00');	$effect(() => {		const context = canvas.getContext('2d');		context.clearRect(0, 0, canvas.width, canvas.height);		context.fillStyle = color;		context.fillRect(0, 0, size, size);	});`</script>`

Replacements: $effect replaces a substantial part of $: {} blocks triggering side-effects.

$effect.pre

Purpose: Run code before the DOM updates.
Usage:

`<script>`	$effect.pre(() =>{' '}	{		// logic here	}	);`</script>`

Replaces: beforeUpdate.

$effect.tracking

Purpose: Check if code is running inside a tracking context.
Usage:

`<script>`console.log('tracking:', $effect.tracking());`</script>`

$props

Purpose: Declare component props.
Usage:

`<script>`let {(prop1, prop2)} = $props();`</script>`

Replaces: export let syntax for declaring props.

$bindable

Purpose: Declare bindable props.
Usage:

`<script>`let {(bindableProp = $bindable('fallback'))} = $props();`</script>`

$inspect

Purpose: Equivalent to console.log but re-runs when its argument changes.
Usage:

`<script>`let count = $state(0); $inspect(count);`</script>`

$host

Purpose: Retrieve the this reference of the custom element.
Usage:

`<script>`	function greet(greeting) {		$host().dispatchEvent(new CustomEvent('greeting', { detail: greeting }));	}`</script>`

Note: Only available inside custom element components on the client-side.

Overview of snippets in svelte 5

Snippets, along with render tags, help create reusable chunks of markup inside your components, reducing duplication and enhancing maintainability.

Snippets Usage

Definition: Use the #snippet syntax to define reusable markup sections.
Basic Example:

{#snippet figure(image)}	`<figure>`		`<img src={image.src} alt={image.caption} width={image.width} height={image.height} />`		`<figcaption>`{image.caption}`</figcaption>`	`</figure>`{/snippet}

Invocation: Render predefined snippets with @render:

{@render figure(image)}

Destructuring Parameters: Parameters can be destructured for concise usage:

{#snippet figure({ src, caption, width, height })}	`<figure>`		`<img alt={caption} {src} {width} {height} />`		`<figcaption>`{caption}`</figcaption>`	`</figure>`{/snippet}

Snippet Scope

Scope Rules: Snippets have lexical scoping rules; they are visible to everything in the same lexical scope:

`<div>`	{#snippet x()}		{#snippet y()}...{/snippet}		`<!-- valid usage -->`		{@render y()}	{/snippet}	`<!-- invalid usage -->`	{@render y()}`</div>``<!-- invalid usage -->`{@render x()}

Recursive References: Snippets can self-reference or reference other snippets:

{#snippet blastoff()}	`<span>`🚀`</span>`{/snippet}{#snippet countdown(n)}	{#if n > 0}		`<span>`{n}...`</span>`		{@render countdown(n - 1)}	{:else}		{@render blastoff()}	{/if}{/snippet}{@render countdown(10)}

Passing Snippets to Components

Direct Passing as Props:

`<script>`	import Table from './Table.svelte';	const fruits = [{ name: 'apples', qty: 5, price: 2 }, ...];`</script>`{#snippet header()}	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`{/snippet}{#snippet row(fruit)}	`<td>`{fruit.name}`</td>`	`<td>`{fruit.qty}`</td>`	`<td>`{fruit.price}`</td>`	`<td>`{fruit.qty * fruit.price}`</td>`{/snippet}`<Table data={fruits} {header} {row} />`

Implicit Binding:

`<table data="{fruits}">`	{#snippet header()}	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`	{/snippet} {#snippet row(fruit)}	`<td>`{fruit.name}`</td>`	`<td>`{fruit.qty}`</td>`	`<td>`{fruit.price}`</td>`	`<td>`{fruit.qty * fruit.price}`</td>`	{/snippet}`</table>`

Children Snippet: Non-snippet content defaults to the children snippet:

`<table data="{fruits}">`	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`	`<!-- additional content -->``</table>``<script>`	let { data, children, row } = $props();`</script>``<table>`	`<thead>`		`<tr>`			{@render children()}		`</tr>`	`</thead>`	`<!-- table body -->``</table>`

Avoid Conflicts: Do not use a prop named children if also providing content inside the component.

Typing Snippets

TypeScript Integration:

`<script lang="ts">`	import type { Snippet } from 'svelte';	let { data, children, row }: {		data: any[];		children: Snippet;		row: Snippet`<[any]>`;	} = $props();`</script>`

Generics for Improved Typing:

`<script lang="ts" generics="T">`	import type { Snippet } from 'svelte';	let { data, children, row }: {		data: T[];		children: Snippet;		row: Snippet`<[T]>`;	} = $props();`</script>`

Creating Snippets Programmatically

Advanced Use: Create snippets programmatically using createRawSnippet where necessary.

Snippets and Slots

Mixing with Slots: Slots are deprecated but still work. Snippets provide more flexibility and power.
Custom Elements: Continue using <slot /> for custom elements as usual.

Sure! Here are the succinct instructions for handling Event Handlers in Svelte 5, tailored for the AI-integrated code editor to help it understand and utilize these features effectively.

Custom Instructions for Svelte 5 Event Handlers in Cursor AI

Overview

In Svelte 5, event handlers are treated as properties, simplifying their use and integrating them more closely with the rest of the properties in the component.

Basic Event Handlers

Declaration: Use properties to attach event handlers.

`<script>`	let count = $state(0);`</script>``<button onclick={() =>` count++}>	clicks: {count}`</button>`

Shorthand Syntax:

`<script>`	let count = $state(0);	function handleClick() {		count++;	}`</script>``<button {handleClick}>`	clicks: {count}`</button>`

Deprecation: The traditional on: directive is deprecated.

Component Events

Replacing createEventDispatcher: Components should accept callback props instead of using createEventDispatcher.

`<script>`	import Pump from './Pump.svelte';	let size = $state(15);	let burst = $state(false);	function reset() {		size = 15;		burst = false;	}`</script>``<Pump	inflate={(power) =>` { size += power; if (size > 75) burst = true; }}	deflate={(power) => { if (size > 0) size -= power; }}/>{#if burst}	`<button onclick={reset}>`new balloon`</button>`	`<span class="boom">`💥`</span>`{:else}	`<span class="balloon" style="scale: {0.01 * size}">` 🎈 `</span>`{/if}

Bubbling Events

Accept Callback Props:

`<script>`	let { onclick, children } = $props();`</script>``<button {onclick}>`	{@render children()}`</button>`

Spreading Props:

`<script>`	let { children, ...props } = $props();`</script>``<button {...props}>`	{@render children()}`</button>`

Event Modifiers

Avoiding Modifiers: Modifiers like |once, |preventDefault, etc., are not supported. Use wrapper functions instead.
Example Wrapper Functions:

`<script>`	function once(fn) {		return function (event) {			if (fn) fn.call(this, event);			fn = null;		};	}	function preventDefault(fn) {		return function (event) {			event.preventDefault();			fn.call(this, event);		};	}`</script>``<button onclick={once(preventDefault(handler))}>`...`</button>`

Special Modifiers: For capture:

`<button onclickcapture={...}>`...`</button>`

Multiple Event Handlers

Combining Handlers: Instead of using multiple handlers, combine them into one.

`<button	onclick={(e) =>` {		handlerOne(e);		handlerTwo(e);	}}>	...`</button>`

examples old vs new

Counter Example

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let count = 0;
$: double = count * 2;
$: {
if (count > 10) alert('Too high!');
}
</script>
<button on:click="{()" ="">count++}> {count} / {double}</button>
```
After:
```html
<script>
let count = $state(0);
let double = $derived(count * 2);
$effect(() => {
if (count > 10) alert('Too high!');
});
</script>
<button onclick="{()" ="">count++}> {count} / {double}</button>
```

Tracking Dependencies

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let a = 0;
let b = 0;
$: sum = add(a, b);
function add(x, y) {
return x + y;
}
</script>
<button on:click="{()" ="">a++}>a++</button>
<button on:click="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```
After:
```html
<script>
let a = $state(0);
let b = $state(0);
let sum = $derived(add());
function add() {
return a + b;
}
</script>
<button onclick="{()" ="">a++}>a++</button>
<button onclick="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```

Untracking Dependencies

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let a = 0;
let b = 0;
$: sum = a + noTrack(b);
function noTrack(value) {
return value;
}
</script>
<button on:click="{()" ="">a++}>a++</button>
<button on:click="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```
After:
```html
<script>
import { untrack } from 'svelte';
let a = $state(0);
let b = $state(0);
let sum = $derived(add());
function add() {
return a + untrack(() => b);
}
</script>
<button onclick="{()" ="">a++}>a++</button>
<button onclick="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```

Simple Component Props

Svelte 5:
```html
<script>
let { count = 0 } = $props();
</script>
{count}
```

Advanced Component Props

Svelte 5:
```html
<script>
let { class: classname, ...others } = $props();
</script>
<pre class="{classname}">
{JSON.stringify(others)}
</pre>
```

Autoscroll Example

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
import { tick, beforeUpdate } from 'svelte';
let theme = 'dark';
let messages = [];
let viewport;
let updatingMessages = false;
beforeUpdate(() => {
if (updatingMessages) {
const autoscroll =
viewport && viewport.offsetHeight + viewport.scrollTop > viewport.scrollHeight - 50;
if (autoscroll) {
tick().then(() => viewport.scrollTo(0, viewport.scrollHeight));
}
}
});
function handleKeydown(event) {
if (event.key === 'Enter') {
const text = event.target.value;
if (text) {
messages = [...messages, text];
updatingMessages = true;
event.target.value = '';
}
}
}
function toggle() {
theme = theme === 'dark' ? 'light' : 'dark';
}
</script>
<div class:dark="{theme" ="" ="" ="dark" }>
<div bind:this="{viewport}">
{#each messages as message}
<p>{message}</p>
{/each}
</div>
<input on:keydown="{handleKeydown}" />
<button on:click="{toggle}">Toggle dark mode</button>
</div>
```
After:
```html
<script>
import { tick } from 'svelte';
let theme = $state('dark');
let messages = $state([]);
let viewport;
$effect.pre(() => {
messages;
const autoscroll =
viewport && viewport.offsetHeight + viewport.scrollTop > viewport.scrollHeight - 50;
if (autoscroll) {
tick().then(() => viewport.scrollTo(0, viewport.scrollHeight));
}
});
function handleKeydown(event) {
if (event.key === 'Enter') {
const text = event.target.value;
if (text) {
messages = [...messages, text];
event.target.value = '';
}
}
}
function toggle() {
theme = theme === 'dark' ? 'light' : 'dark';
}
</script>
<div class:dark="{theme" ="" ="" ="dark" }>
<div bind:this="{viewport}">
{#each messages as message}
<p>{message}</p>
{/each}
</div>
<input onkeydown="{handleKeydown}" />
<button onclick="{toggle}">Toggle dark mode</button>
</div>
```

Forwarding Events

Svelte 5:
```html
<script>
let { ...props } = $props();
</script>
<button {...props}>a button</button>
```

Passing UI Content to a Component

Passing content using snippets:
```html

<script>
import Button from './Button.svelte';
</script>
<button>{#snippet children(prop)} click {prop} {/snippet}</button>

<script>
let { children } = $props();
</script>
<button>{@render children("some value")}</button>
```

I'm also using sveltekit 2 which also has some changes I'd like you to keep in mind

Redirect and Error Handling

In SvelteKit 2, it is no longer necessary to throw the results of error(...) and redirect(...). Simply calling them is sufficient.

SvelteKit 1:

import { error } from '@sveltejs/kit';function load() {	throw error(500, 'something went wrong');}

SvelteKit 2:

import { error } from '@sveltejs/kit';function load() {	error(500, 'something went wrong');}

Distinguish Errors:
Use isHttpError and isRedirect to differentiate known errors from unexpected ones.

import { isHttpError, isRedirect } from '@sveltejs/kit';try {	// some code} catch (err) {	if (isHttpError(err) || isRedirect(err)) {		// handle error	}}

Cookies now require a specified path when set, deleted, or serialized.

SvelteKit 1:

export function load({ cookies }) {	cookies.set(name, value);	return { response };}

SvelteKit 2:

export function load({ cookies }) {	cookies.set(name, value, { path: '/' });	return { response };}

Top-Level Promise Handling

Promises in load functions are no longer awaited automatically.

Single Promise:

SvelteKit 1:

export function load({ fetch }) {    return {        response: fetch(...).then(r => r.json())    };}

SvelteKit 2:

export async function load({ fetch }) {    const response = await fetch(...).then(r => r.json());    return { response };}

Multiple Promises:

SvelteKit 1:

export function load({ fetch }) {    return {        a: fetch(...).then(r => r.json()),        b: fetch(...).then(r => r.json())    };}

SvelteKit 2:

export async function load({ fetch }) {    const [a, b] = await Promise.all([        fetch(...).then(r => r.json()),        fetch(...).then(r => r.json())    ]);    return { a, b };}

`goto` Changes

goto(...) no longer accepts external URLs. Use window.location.href = url for external navigation.

Relative Paths Default

Paths are now relative by default, ensuring portability across different environments. The paths.relative config option manages this behavior.

Deprecated Settings and Functions

Server Fetches are no longer trackable.
preloadCode Arguments: Must be prefixed with the base path.
resolvePath Replacement: Use resolveRoute instead.

import { resolveRoute } from '$app/paths';const path = resolveRoute('/blog/[slug]', { slug: 'hello' });

Improved Error Handling

Errors trigger the handleError hook with status and message properties for better discernment.

Dynamic Environment Variables

Dynamic environment variables cannot be used during prerendering. Use static modules instead.

`use:enhance` Callback Changes

The properties form and data have been removed from use:enhance callbacks, replaced by formElement and formData.

Forms with File Inputs

Forms containing <input type="file"> must use enctype="multipart/form-data".

With these adjusted guidelines, your AI can now generate SvelteKit 2 code accurately while considering the migration changes.

stack:

Svelte 5

Sveltekit 2

TypeScript

Svelte 5 SvelteKit 2 .cursorrules prompt file

Sumanth Chinthagunta

NEW

Svelte 5 vs Svelte 4 .cursorrules prompt file

I'm using svelte 5 instead of svelte 4 here is an overview of the changes.

Overview

Svelte 5 introduces runes, a set of advanced primitives for controlling reactivity. The runes replace certain non-runes features and provide more explicit control over state and effects.

$state

Purpose: Declare reactive state.
Usage:

`<script>`let count = $state(0);`</script>`

Replaces: Top-level let declarations in non-runes mode.
Class Fields:

class Todo {	done = $state(false);	text = $state();	constructor(text) {		this.text = text;	}}

Deep Reactivity: Only plain objects and arrays become deeply reactive.

$state.raw

Purpose: Declare state that cannot be mutated, only reassigned.
Usage:

`<script>`let numbers = $state.raw([1, 2, 3]);`</script>`

Performance: Improves with large arrays and objects.

$state.snapshot

Purpose: Take a static snapshot of $state.
Usage:

`<script>`	let counter = $state({ count: 0 });	function onClick() {		console.log($state.snapshot(counter));	}`</script>`

$derived

Purpose: Declare derived state.
Usage:

`<script>`let count = $state(0); let doubled = $derived(count * 2);`</script>`

Replaces: Reactive variables computed using $: in non-runes mode.

$derived.by

Purpose: Create complex derivations with a function.
Usage:

`<script>`	let numbers = $state([1, 2, 3]); let total = $derived.by(() => numbers.reduce((a, b) => a + b,	0));`</script>`

$effect

Purpose: Run side-effects when values change.
Usage:

`<script>`	let size = $state(50);	let color = $state('#ff3e00');	$effect(() => {		const context = canvas.getContext('2d');		context.clearRect(0, 0, canvas.width, canvas.height);		context.fillStyle = color;		context.fillRect(0, 0, size, size);	});`</script>`

Replacements: $effect replaces a substantial part of $: {} blocks triggering side-effects.

$effect.pre

Purpose: Run code before the DOM updates.
Usage:

`<script>`	$effect.pre(() =>{' '}	{		// logic here	}	);`</script>`

Replaces: beforeUpdate.

$effect.tracking

Purpose: Check if code is running inside a tracking context.
Usage:

`<script>`console.log('tracking:', $effect.tracking());`</script>`

$props

Purpose: Declare component props.
Usage:

`<script>`let {(prop1, prop2)} = $props();`</script>`

Replaces: export let syntax for declaring props.

$bindable

Purpose: Declare bindable props.
Usage:

`<script>`let {(bindableProp = $bindable('fallback'))} = $props();`</script>`

$inspect

Purpose: Equivalent to console.log but re-runs when its argument changes.
Usage:

`<script>`let count = $state(0); $inspect(count);`</script>`

$host

Purpose: Retrieve the this reference of the custom element.
Usage:

`<script>`	function greet(greeting) {		$host().dispatchEvent(new CustomEvent('greeting', { detail: greeting }));	}`</script>`

Note: Only available inside custom element components on the client-side.

Overview of snippets in svelte 5

Snippets, along with render tags, help create reusable chunks of markup inside your components, reducing duplication and enhancing maintainability.

Snippets Usage

Definition: Use the #snippet syntax to define reusable markup sections.
Basic Example:

{#snippet figure(image)}	`<figure>`		`<img src={image.src} alt={image.caption} width={image.width} height={image.height} />`		`<figcaption>`{image.caption}`</figcaption>`	`</figure>`{/snippet}

Invocation: Render predefined snippets with @render:

{@render figure(image)}

Destructuring Parameters: Parameters can be destructured for concise usage:

{#snippet figure({ src, caption, width, height })}	`<figure>`		`<img alt={caption} {src} {width} {height} />`		`<figcaption>`{caption}`</figcaption>`	`</figure>`{/snippet}

Snippet Scope

Scope Rules: Snippets have lexical scoping rules; they are visible to everything in the same lexical scope:

`<div>`	{#snippet x()}		{#snippet y()}...{/snippet}		`<!-- valid usage -->`		{@render y()}	{/snippet}	`<!-- invalid usage -->`	{@render y()}`</div>``<!-- invalid usage -->`{@render x()}

Recursive References: Snippets can self-reference or reference other snippets:

{#snippet blastoff()}	`<span>`🚀`</span>`{/snippet}{#snippet countdown(n)}	{#if n > 0}		`<span>`{n}...`</span>`		{@render countdown(n - 1)}	{:else}		{@render blastoff()}	{/if}{/snippet}{@render countdown(10)}

Passing Snippets to Components

Direct Passing as Props:

`<script>`	import Table from './Table.svelte';	const fruits = [{ name: 'apples', qty: 5, price: 2 }, ...];`</script>`{#snippet header()}	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`{/snippet}{#snippet row(fruit)}	`<td>`{fruit.name}`</td>`	`<td>`{fruit.qty}`</td>`	`<td>`{fruit.price}`</td>`	`<td>`{fruit.qty * fruit.price}`</td>`{/snippet}`<Table data={fruits} {header} {row} />`

Implicit Binding:

`<table data="{fruits}">`	{#snippet header()}	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`	{/snippet} {#snippet row(fruit)}	`<td>`{fruit.name}`</td>`	`<td>`{fruit.qty}`</td>`	`<td>`{fruit.price}`</td>`	`<td>`{fruit.qty * fruit.price}`</td>`	{/snippet}`</table>`

Children Snippet: Non-snippet content defaults to the children snippet:

`<table data="{fruits}">`	`<th>`fruit`</th>`	`<th>`qty`</th>`	`<th>`price`</th>`	`<th>`total`</th>`	`<!-- additional content -->``</table>``<script>`	let { data, children, row } = $props();`</script>``<table>`	`<thead>`		`<tr>`			{@render children()}		`</tr>`	`</thead>`	`<!-- table body -->``</table>`

Avoid Conflicts: Do not use a prop named children if also providing content inside the component.

Typing Snippets

TypeScript Integration:

`<script lang="ts">`	import type { Snippet } from 'svelte';	let { data, children, row }: {		data: any[];		children: Snippet;		row: Snippet`<[any]>`;	} = $props();`</script>`

Generics for Improved Typing:

`<script lang="ts" generics="T">`	import type { Snippet } from 'svelte';	let { data, children, row }: {		data: T[];		children: Snippet;		row: Snippet`<[T]>`;	} = $props();`</script>`

Creating Snippets Programmatically

Advanced Use: Create snippets programmatically using createRawSnippet where necessary.

Snippets and Slots

Mixing with Slots: Slots are deprecated but still work. Snippets provide more flexibility and power.
Custom Elements: Continue using <slot /> for custom elements as usual.

Sure! Here are the succinct instructions for handling Event Handlers in Svelte 5, tailored for the AI-integrated code editor to help it understand and utilize these features effectively.

Custom Instructions for Svelte 5 Event Handlers in Cursor AI

Overview

In Svelte 5, event handlers are treated as properties, simplifying their use and integrating them more closely with the rest of the properties in the component.

Basic Event Handlers

Declaration: Use properties to attach event handlers.

`<script>`	let count = $state(0);`</script>``<button onclick={() =>` count++}>	clicks: {count}`</button>`

Shorthand Syntax:

`<script>`	let count = $state(0);	function handleClick() {		count++;	}`</script>``<button {handleClick}>`	clicks: {count}`</button>`

Deprecation: The traditional on: directive is deprecated.

Component Events

Replacing createEventDispatcher: Components should accept callback props instead of using createEventDispatcher.

`<script>`	import Pump from './Pump.svelte';	let size = $state(15);	let burst = $state(false);	function reset() {		size = 15;		burst = false;	}`</script>``<Pump	inflate={(power) =>` { size += power; if (size > 75) burst = true; }}	deflate={(power) => { if (size > 0) size -= power; }}/>{#if burst}	`<button onclick={reset}>`new balloon`</button>`	`<span class="boom">`💥`</span>`{:else}	`<span class="balloon" style="scale: {0.01 * size}">` 🎈 `</span>`{/if}

Bubbling Events

Accept Callback Props:

`<script>`	let { onclick, children } = $props();`</script>``<button {onclick}>`	{@render children()}`</button>`

Spreading Props:

`<script>`	let { children, ...props } = $props();`</script>``<button {...props}>`	{@render children()}`</button>`

Event Modifiers

Avoiding Modifiers: Modifiers like |once, |preventDefault, etc., are not supported. Use wrapper functions instead.
Example Wrapper Functions:

`<script>`	function once(fn) {		return function (event) {			if (fn) fn.call(this, event);			fn = null;		};	}	function preventDefault(fn) {		return function (event) {			event.preventDefault();			fn.call(this, event);		};	}`</script>``<button onclick={once(preventDefault(handler))}>`...`</button>`

Special Modifiers: For capture:

`<button onclickcapture={...}>`...`</button>`

Multiple Event Handlers

Combining Handlers: Instead of using multiple handlers, combine them into one.

`<button	onclick={(e) =>` {		handlerOne(e);		handlerTwo(e);	}}>	...`</button>`

examples old vs new

Counter Example

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let count = 0;
$: double = count * 2;
$: {
if (count > 10) alert('Too high!');
}
</script>
<button on:click="{()" ="">count++}> {count} / {double}</button>
```
After:
```html
<script>
let count = $state(0);
let double = $derived(count * 2);
$effect(() => {
if (count > 10) alert('Too high!');
});
</script>
<button onclick="{()" ="">count++}> {count} / {double}</button>
```

Tracking Dependencies

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let a = 0;
let b = 0;
$: sum = add(a, b);
function add(x, y) {
return x + y;
}
</script>
<button on:click="{()" ="">a++}>a++</button>
<button on:click="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```
After:
```html
<script>
let a = $state(0);
let b = $state(0);
let sum = $derived(add());
function add() {
return a + b;
}
</script>
<button onclick="{()" ="">a++}>a++</button>
<button onclick="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```

Untracking Dependencies

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
let a = 0;
let b = 0;
$: sum = a + noTrack(b);
function noTrack(value) {
return value;
}
</script>
<button on:click="{()" ="">a++}>a++</button>
<button on:click="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```
After:
```html
<script>
import { untrack } from 'svelte';
let a = $state(0);
let b = $state(0);
let sum = $derived(add());
function add() {
return a + untrack(() => b);
}
</script>
<button onclick="{()" ="">a++}>a++</button>
<button onclick="{()" ="">b++}>b++</button>
<p>{a} + {b} = {sum}</p>
```

Simple Component Props

Svelte 5:
```html
<script>
let { count = 0 } = $props();
</script>
{count}
```

Advanced Component Props

Svelte 5:
```html
<script>
let { class: classname, ...others } = $props();
</script>
<pre class="{classname}">
{JSON.stringify(others)}
</pre>
```

Autoscroll Example

Svelte 4 vs. Svelte 5:
Before:
```html
<script>
import { tick, beforeUpdate } from 'svelte';
let theme = 'dark';
let messages = [];
let viewport;
let updatingMessages = false;
beforeUpdate(() => {
if (updatingMessages) {
const autoscroll =
viewport && viewport.offsetHeight + viewport.scrollTop > viewport.scrollHeight - 50;
if (autoscroll) {
tick().then(() => viewport.scrollTo(0, viewport.scrollHeight));
}
}
});
function handleKeydown(event) {
if (event.key === 'Enter') {
const text = event.target.value;
if (text) {
messages = [...messages, text];
updatingMessages = true;
event.target.value = '';
}
}
}
function toggle() {
theme = theme === 'dark' ? 'light' : 'dark';
}
</script>
<div class:dark="{theme" ="" ="" ="dark" }>
<div bind:this="{viewport}">
{#each messages as message}
<p>{message}</p>
{/each}
</div>
<input on:keydown="{handleKeydown}" />
<button on:click="{toggle}">Toggle dark mode</button>
</div>
```
After:
```html
<script>
import { tick } from 'svelte';
let theme = $state('dark');
let messages = $state([]);
let viewport;
$effect.pre(() => {
messages;
const autoscroll =
viewport && viewport.offsetHeight + viewport.scrollTop > viewport.scrollHeight - 50;
if (autoscroll) {
tick().then(() => viewport.scrollTo(0, viewport.scrollHeight));
}
});
function handleKeydown(event) {
if (event.key === 'Enter') {
const text = event.target.value;
if (text) {
messages = [...messages, text];
event.target.value = '';
}
}
}
function toggle() {
theme = theme === 'dark' ? 'light' : 'dark';
}
</script>
<div class:dark="{theme" ="" ="" ="dark" }>
<div bind:this="{viewport}">
{#each messages as message}
<p>{message}</p>
{/each}
</div>
<input onkeydown="{handleKeydown}" />
<button onclick="{toggle}">Toggle dark mode</button>
</div>
```

Forwarding Events

Svelte 5:
```html
<script>
let { ...props } = $props();
</script>
<button {...props}>a button</button>
```

Passing UI Content to a Component

Passing content using snippets:
```html

<script>
import Button from './Button.svelte';
</script>
<button>{#snippet children(prop)} click {prop} {/snippet}</button>

<script>
let { children } = $props();
</script>
<button>{@render children("some value")}</button>
```

stack:

Svelte 5 vs Svelte 4 .cursorrules prompt file

Adam Shand

NEW

SvelteKit TypeScript Guide .cursorrules prompt file

You are an expert in Svelte 5, SvelteKit, TypeScript, Supabase, Drizzle and modern web development.

Key Principles

Write concise, technical code with accurate Svelte 5 and SvelteKit examples.
Leverage SvelteKit's server-side rendering (SSR) and static site generation (SSG) capabilities.
Prioritize performance optimization and minimal JavaScript for optimal user experience.
Use descriptive variable names and follow Svelte and SvelteKit conventions.
Organize files using SvelteKit's file-based routing system.
Write concise, technical responses with accurate TypeScript examples.
Use functional, declarative programming. Avoid classes.
Prefer iteration and modularization over duplication.
Use descriptive variable names with auxiliary verbs (e.g., isLoading, hasError).
Use lowercase with dashes for directories (e.g., components/auth-wizard).
Favor named exports for components.
Use the Receive an Object, Return an Object (RORO) pattern.

Code Style and Structure

Write concise, TypeScript code with accurate examples.
Use functional and declarative programming patterns; avoid unnecessary classes except for state machines.
Prefer iteration and modularization over code duplication.
Structure files: component logic, markup, styles, helpers, types.
Follow Svelte's official documentation for setup and configuration: https://svelte.dev/docs
Use "function" keyword for pure functions. Omit semicolons.
Use TypeScript for all code. Prefer interfaces over types.
File structure: Exported component, subcomponents, helpers, static content, types.
Avoid unnecessary curly braces in conditional statements.
For single-line statements in conditionals, omit curly braces.
Use concise, one-line syntax for simple conditional statements (e.g., if (condition) doSomething()).
-Implement the preload pattern to prevent waterfalls.
Leverage Supabase for real-time data synchronization and state management.

Naming Conventions

Use lowercase with hyphens for component files (e.g., components/auth-form.svelte).
Use PascalCase for component names in imports and usage.
Use camelCase for variables, functions, and props.

TypeScript Usage

Use TypeScript for all code; prefer interfaces over types.
Avoid enums; use const objects instead.
Use functional components with TypeScript interfaces for props.
Enable strict mode in TypeScript for better type safety.

Svelte Runes

$state: Declare reactive state
```typescript
let count = $state(0);
```
$derived: Compute derived values
```typescript
let doubled = $derived(count * 2);
```
$effect: Manage side effects and lifecycle
```typescript
$effect(() => {
console.log(Count is now ${count});
});
```
$props: Declare component props
```typescript
let { optionalProp = 42, requiredProp } = $props();
```
$bindable: Create two-way bindable props
```typescript
let { bindableProp = $bindable() } = $props();
```
$inspect: Debug reactive state (development only)
```typescript
$inspect(count);
```

UI and Styling

Use Tailwind CSS for utility-first styling approach.
Leverage Shadcn components for pre-built, customizable UI elements.
Import Shadcn components from $lib/components/ui.
Organize Tailwind classes using the cn() utility from $lib/utils.
Use Svelte's built-in transition and animation features.

Shadcn Color Conventions

Use background and foreground convention for colors.
Define CSS variables without color space function:
```css
--primary: 222.2 47.4% 11.2%;
--primary-foreground: 210 40% 98%;
```
Usage example:
```svelte
<div class="bg-primary text-primary-foreground">Hello</div>
```
Key color variables:
--background, --foreground: Default body colors
--muted, --muted-foreground: Muted backgrounds
--card, --card-foreground: Card backgrounds
--popover, --popover-foreground: Popover backgrounds
--border: Default border color
--input: Input border color
--primary, --primary-foreground: Primary button colors
--secondary, --secondary-foreground: Secondary button colors
--accent, --accent-foreground: Accent colors
--destructive, --destructive-foreground: Destructive action colors
--ring: Focus ring color
--radius: Border radius for components

SvelteKit Project Structure

Use the recommended SvelteKit project structure:
```
src/
- lib/
- routes/
- app.html
static/
svelte.config.js
vite.config.js
```

Component Development

Create .svelte files for Svelte components.
Use .svelte.ts files for component logic and state machines.
Implement proper component composition and reusability.
Use Svelte's props for data passing.
Leverage Svelte's reactive declarations for local state management.

State Management

Use classes for complex state management (state machines):
```typescript
// counter.svelte.ts
class Counter {
count = $state(0);
incrementor = $state(1);
increment() {
this.count += this.incrementor;
}
resetCount() {
this.count = 0;
}
resetIncrementor() {
this.incrementor = 1;
}
}
export const counter = new Counter();
```
Use in components:
```svelte
<script lang="ts">
import { counter } from './counter.svelte.ts';
</script>
<button on:click={() => counter.increment()}>
Count: {counter.count}
</button>
```

Routing and Pages

Utilize SvelteKit's file-based routing system in the src/routes/ directory.
Implement dynamic routes using [slug] syntax.
Use load functions for server-side data fetching and pre-rendering.
Implement proper error handling with +error.svelte pages.

Server-Side Rendering (SSR) and Static Site Generation (SSG)

Leverage SvelteKit's SSR capabilities for dynamic content.
Implement SSG for static pages using prerender option.
Use the adapter-auto for automatic deployment configuration.

Performance Optimization

Leverage Svelte's compile-time optimizations.
Use {#key} blocks to force re-rendering of components when needed.
Implement code splitting using dynamic imports for large applications.
Profile and monitor performance using browser developer tools.
Use $effect.tracking() to optimize effect dependencies.
Minimize use of client-side JavaScript; leverage SvelteKit's SSR and SSG.
Implement proper lazy loading for images and other assets.

Data Fetching and API Routes

Use load functions for server-side data fetching.
Implement proper error handling for data fetching operations.
Create API routes in the src/routes/api/ directory.
Implement proper request handling and response formatting in API routes.
Use SvelteKit's hooks for global API middleware.

SEO and Meta Tags

Use Svelte:head component for adding meta information.
Implement canonical URLs for proper SEO.
Create reusable SEO components for consistent meta tag management.

Forms and Actions

Utilize SvelteKit's form actions for server-side form handling.
Implement proper client-side form validation using Svelte's reactive declarations.
Use progressive enhancement for JavaScript-optional form submissions.

Internationalization (i18n) with Paraglide.js

Use Paraglide.js for internationalization: https://inlang.com/m/gerre34r/library-inlang-paraglideJs
Install Paraglide.js: npm install @inlang/paraglide-js
Set up language files in the languages directory.
Use the t function to translate strings:
```svelte
<script>
import { t } from '@inlang/paraglide-js';
</script>
<h1>{t('welcome_message')}</h1>
```
Support multiple languages and RTL layouts.
Ensure text scaling and font adjustments for accessibility.

Accessibility

Ensure proper semantic HTML structure in Svelte components.
Implement ARIA attributes where necessary.
Ensure keyboard navigation support for interactive elements.
Use Svelte's bind:this for managing focus programmatically.

Key Conventions

Embrace Svelte's simplicity and avoid over-engineering solutions.
Use SvelteKit for full-stack applications with SSR and API routes.
Prioritize Web Vitals (LCP, FID, CLS) for performance optimization.
Use environment variables for configuration management.
Follow Svelte's best practices for component composition and state management.
Ensure cross-browser compatibility by testing on multiple platforms.
Keep your Svelte and SvelteKit versions up to date.
Use the @supabase/ssr package instead of the older auth helpers packages.
Configure your Supabase client to use cookies for storing session information.
Implement the PKCE (Proof Key for Code Exchange) flow for authentication in SSR applications.
Create separate browser and server clients using the createBrowserClient and createServerClient functions.
Store access and refresh tokens in secure cookies for SSR.
Implement proper error handling for invalid refresh token errors on the server-side.
Use environment variables to store Supabase URL and API keys.
Implement Row Level Security (RLS) on all tables containing sensitive data.
Adopt a multi-stage development workflow (local -> staging -> prod).
Use database migration tools to manage schema changes.
Optimize queries, indexes, and connection management regularly.
Implement proper CORS settings in your Supabase project.
Use TypeScript for better type safety and developer experience.
Implement consistent error handling across your application.
Use a logging service for production environments to track errors and performance issues.
Implement unit tests for database interactions.

Documentation:
[2] https://supabase.com/docs/guides/auth/server-side
[3] https://supabase.com/docs/guides/auth/server-side/creating-a-client
[4] https://www.reddit.com/r/Supabase/comments/17hbwqb/question_about_supabasessr_and/
[5] https://supabase.com/docs/guides/auth/server-side/advanced-guide
[6] https://www.restack.io/docs/supabase-knowledge-supabase-documentation
[8] https://github.com/supabase/supabase/milestones

Documentation

Svelte 5 Runes: https://svelte-5-preview.vercel.app/docs/runes
Svelte Documentation: https://svelte.dev/docs
SvelteKit Documentation: https://kit.svelte.dev/docs
Paraglide.js Documentation: https://inlang.com/m/gerre34r/library-inlang-paraglideJs/usage

Refer to Svelte, SvelteKit, and Paraglide.js documentation for detailed information on components, internationalization, and best practices.

stack:

SvelteKit TypeScript Guide .cursorrules prompt file

Brandon Edley

NEW

Web App Optimization .cursorrules prompt file

You are an expert in Svelte 5, SvelteKit, TypeScript, and modern web development.

Key Principles

- Write concise, technical code with accurate Svelte 5 and SvelteKit examples.
- Leverage SvelteKit's server-side rendering (SSR) and static site generation (SSG) capabilities.
- Prioritize performance optimization and minimal JavaScript for optimal user experience.
- Use descriptive variable names and follow Svelte and SvelteKit conventions.
- Organize files using SvelteKit's file-based routing system.

Code Style and Structure

- Write concise, technical TypeScript or JavaScript code with accurate examples.
- Use functional and declarative programming patterns; avoid unnecessary classes except for state machines.
- Prefer iteration and modularization over code duplication.
- Structure files: component logic, markup, styles, helpers, types.
- Follow Svelte's official documentation for setup and configuration: https://svelte.dev/docs

Naming Conventions

- Use lowercase with hyphens for component files (e.g., `components/auth-form.svelte`).
- Use PascalCase for component names in imports and usage.
- Use camelCase for variables, functions, and props.

TypeScript Usage

- Use TypeScript for all code; prefer interfaces over types.
- Avoid enums; use const objects instead.
- Use functional components with TypeScript interfaces for props.
- Enable strict mode in TypeScript for better type safety.

Svelte Runes

- `$state`: Declare reactive state
```typescript
let count = $state(0);
```
- `$derived`: Compute derived values
```typescript
let doubled = $derived(count * 2);
```
- `$effect`: Manage side effects and lifecycle
```typescript
$effect(() => {
console.log(`Count is now ${count}`);
});
```
- `$props`: Declare component props
```typescript
let { optionalProp = 42, requiredProp } = $props();
```
- `$bindable`: Create two-way bindable props
```typescript
let { bindableProp = $bindable() } = $props();
```
- `$inspect`: Debug reactive state (development only)
```typescript
$inspect(count);
```

UI and Styling

- Use Tailwind CSS for utility-first styling approach.
- Leverage Shadcn components for pre-built, customizable UI elements.
- Import Shadcn components from `$lib/components/ui`.
- Organize Tailwind classes using the `cn()` utility from `$lib/utils`.
- Use Svelte's built-in transition and animation features.

Shadcn Color Conventions

- Use `background` and `foreground` convention for colors.
- Define CSS variables without color space function:
```css
--primary: 222.2 47.4% 11.2%;
--primary-foreground: 210 40% 98%;
```
- Usage example:
```svelte
<div class="bg-primary text-primary-foreground">Hello</div>
```
- Key color variables:
- `--background`, `--foreground`: Default body colors
- `--muted`, `--muted-foreground`: Muted backgrounds
- `--card`, `--card-foreground`: Card backgrounds
- `--popover`, `--popover-foreground`: Popover backgrounds
- `--border`: Default border color
- `--input`: Input border color
- `--primary`, `--primary-foreground`: Primary button colors
- `--secondary`, `--secondary-foreground`: Secondary button colors
- `--accent`, `--accent-foreground`: Accent colors
- `--destructive`, `--destructive-foreground`: Destructive action colors
- `--ring`: Focus ring color
- `--radius`: Border radius for components

SvelteKit Project Structure

- Use the recommended SvelteKit project structure:
```
- src/
  - lib/
  - routes/
  - app.html
- static/
- svelte.config.js
- vite.config.js
```

Component Development

- Create .svelte files for Svelte components.
- Use .svelte.ts files for component logic and state machines.
- Implement proper component composition and reusability.
- Use Svelte's props for data passing.
- Leverage Svelte's reactive declarations for local state management.

State Management

- Use classes for complex state management (state machines):

```typescript
// counter.svelte.ts
class Counter {
count = $state(0);
incrementor = $state(1);

increment() {
this.count += this.incrementor;
}

resetCount() {
this.count = 0;
}

resetIncrementor() {
this.incrementor = 1;
}
}

export const counter = new Counter();
```

- Use in components:

```svelte
<script lang="ts">
import { counter } from './counter.svelte.ts';
</script>

<button on:click={() => counter.increment()}>
Count: {counter.count}
</button>
```

Routing and Pages

- Utilize SvelteKit's file-based routing system in the src/routes/ directory.
- Implement dynamic routes using [slug] syntax.
- Use load functions for server-side data fetching and pre-rendering.
- Implement proper error handling with +error.svelte pages.

Server-Side Rendering (SSR) and Static Site Generation (SSG)

- Leverage SvelteKit's SSR capabilities for dynamic content.
- Implement SSG for static pages using prerender option.
- Use the adapter-auto for automatic deployment configuration.

Performance Optimization

- Leverage Svelte's compile-time optimizations.
- Use `{#key}` blocks to force re-rendering of components when needed.
- Implement code splitting using dynamic imports for large applications.
- Profile and monitor performance using browser developer tools.
- Use `$effect.tracking()` to optimize effect dependencies.
- Minimize use of client-side JavaScript; leverage SvelteKit's SSR and SSG.
- Implement proper lazy loading for images and other assets.

Data Fetching and API Routes

- Use load functions for server-side data fetching.
- Implement proper error handling for data fetching operations.
- Create API routes in the src/routes/api/ directory.
- Implement proper request handling and response formatting in API routes.
- Use SvelteKit's hooks for global API middleware.

SEO and Meta Tags

- Use Svelte:head component for adding meta information.
- Implement canonical URLs for proper SEO.
- Create reusable SEO components for consistent meta tag management.

Forms and Actions

- Utilize SvelteKit's form actions for server-side form handling.
- Implement proper client-side form validation using Svelte's reactive declarations.
- Use progressive enhancement for JavaScript-optional form submissions.

Internationalization (i18n) with Paraglide.js

- Use Paraglide.js for internationalization: https://inlang.com/m/gerre34r/library-inlang-paraglideJs
- Install Paraglide.js: `npm install @inlang/paraglide-js`
- Set up language files in the `languages` directory.
- Use the `t` function to translate strings:

```svelte
<script>
import { t } from '@inlang/paraglide-js';
</script>

<h1>{t('welcome_message')}</h1>
```

- Support multiple languages and RTL layouts.
- Ensure text scaling and font adjustments for accessibility.

Accessibility

- Ensure proper semantic HTML structure in Svelte components.
- Implement ARIA attributes where necessary.
- Ensure keyboard navigation support for interactive elements.
- Use Svelte's bind:this for managing focus programmatically.

Key Conventions

1. Embrace Svelte's simplicity and avoid over-engineering solutions.
2. Use SvelteKit for full-stack applications with SSR and API routes.
3. Prioritize Web Vitals (LCP, FID, CLS) for performance optimization.
4. Use environment variables for configuration management.
5. Follow Svelte's best practices for component composition and state management.
6. Ensure cross-browser compatibility by testing on multiple platforms.
7. Keep your Svelte and SvelteKit versions up to date.

Documentation

- Svelte 5 Runes: https://svelte-5-preview.vercel.app/docs/runes
- Svelte Documentation: https://svelte.dev/docs
- SvelteKit Documentation: https://kit.svelte.dev/docs
- Paraglide.js Documentation: https://inlang.com/m/gerre34r/library-inlang-paraglideJs/usage

Refer to Svelte, SvelteKit, and Paraglide.js documentation for detailed information on components, internationalization, and best practices.

stack: