API Routes with +server.js

Create REST API endpoints using +server.js files.

Basic API Route

javascript
// src/routes/api/posts/+server.js
import { json } from '@sveltejs/kit';

export async function GET() {
  const posts = await db.posts.findMany();
  return json(posts);
}

export async function POST({ request }) {
  const data = await request.json();
  const post = await db.posts.create({ data });
  return json(post, { status: 201 });
}

HTTP Methods

javascript
// +server.js
import { json, error } from '@sveltejs/kit';

export async function GET({ url }) {
  const limit = Number(url.searchParams.get('limit') ?? 10);
  const posts = await getPosts(limit);
  return json(posts);
}

export async function POST({ request }) {
  const data = await request.json();
  const post = await createPost(data);
  return json(post, { status: 201 });
}

export async function PUT({ request, params }) {
  const data = await request.json();
  const post = await updatePost(params.id, data);
  return json(post);
}

export async function DELETE({ params }) {
  await deletePost(params.id);
  return new Response(null, { status: 204 });
}

Dynamic API Routes

javascript
// src/routes/api/posts/[id]/+server.js
import { json, error } from '@sveltejs/kit';

export async function GET({ params }) {
  const post = await getPost(params.id);
  
  if (!post) {
    throw error(404, 'Post not found');
  }
  
  return json(post);
}

Setting Headers

javascript
export async function GET() {
  const data = await getData();
  
  return json(data, {
    headers: {
      'Cache-Control': 'max-age=3600',
      'X-Custom-Header': 'value'
    }
  });
}

Handling Different Content Types

javascript
export async function GET({ request }) {
  const accept = request.headers.get('Accept');
  const data = await getData();
  
  if (accept?.includes('text/csv')) {
    const csv = convertToCSV(data);
    return new Response(csv, {
      headers: { 'Content-Type': 'text/csv' }
    });
  }
  
  return json(data);
}

📖 API routes documentation