sveltekit-data-flow

Original：🇺🇸 English

Translated

SvelteKit data flow guidance. Use for load functions, form actions, server/client data, and invalidation. Covers +page.server.ts vs +page.ts, serialization, fail(), redirect(), error(), invalidateAll().

1installs

Sourcespences10/svelte-skills-kit

Added on2026-02-04

NPX Install

npx skill4agent add spences10/svelte-skills-kit sveltekit-data-flow

SKILL.md Content

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SvelteKit Data Flow

Quick Start

Which file? Server-only (DB/secrets):

+page.server.ts

| Universal (runs both):

+page.ts

| API:

+server.ts

Load decision: Need server resources? → server load | Need client APIs? → universal load

Form actions: Always

+page.server.ts

. Return

fail()

for errors, throw

redirect()

to navigate, throw

error()

for failures.

Example

typescript

// +page.server.ts
import { fail, redirect } from '@sveltejs/kit';

export const load = async ({ locals }) => {
	const user = await db.users.get(locals.userId);
	return { user }; // Must be JSON-serializable
};

export const actions = {
	default: async ({ request }) => {
		const data = await request.formData();
		const email = data.get('email');

		if (!email) return fail(400, { email, missing: true });

		await updateEmail(email);
		throw redirect(303, '/success');
	},
};

Reference Files

load-functions.md - Server vs universal
form-actions.md - Form handling patterns
serialization.md - What can/can't serialize
error-redirect-handling.md - fail/redirect/error
client-auth-invalidation.md - invalidateAll() after client-side auth

Notes

Server load → universal load via
```
data
```
param | ALWAYS
```
throw redirect()/error()
```
No class instances/functions from server load (not serializable)
Last verified: 2025-01-11