SvelteKit

SvelteKit is the meta-framework for Svelte, similar to Next.js for React. It uses standard Web APIs and provides routing, server-side rendering, and API endpoints.

When to Use

• Svelte Apps: The standard way to build Svelte apps in 2025.
• Full Stack: Unified backend and frontend.
• Edge Deployment: Runs on any platform via Adapters (Vercel, Cloudflare, Netlify, Node).

Quick Start

File-based routing in src/routes.

<!-- src/routes/+page.svelte -->
<script>
  let { data } = $props(); // Received from +page.server.js
</script>

<h1>{data.title}</h1>

// src/routes/+page.server.js
export function load() {
  return { title: "Hello from Server" };
}

Core Concepts

Load Functions

load functions in +page.server.js run before the page renders, fetching data. The data is typed automatically in the component.

Form Actions

Handle form submissions in +page.server.js exports named actions.

export const actions = {
  default: async ({ request }) => {
    const data = await request.formData();
    // save to db
  },
};

Adapters

Deployment targets are plugins. adapter-auto, adapter-node, adapter-cloudflare.

Best Practices (2025)

Do:

• Use Svelte 5 Runes: SvelteKit 2+ fully supports Runes mode.
• Use App.State: New SvelteKit interface for typesafe global app state.
• Stream Data: Return promises in load functions to stream non-critical data.

Don’t:

• Don’t use store for server data: Use page.data (Context) for data passing down the tree to avoid state leakage on valid server execution.

References

• SvelteKit Documentation