@eslym/sveltekit-adapter-bun

Another sveltekit adapter for bun, an alternative to svelte-adapter-bun. This package support websocket in dev mode with few steps of setup.

Installation

bun add -d @eslym/sveltekit-adapter-bun

Setup dev server

[!NOTE]
You do not need to do this if you are not using websocket in dev mode.

1. Create an entrypoint file for dev server, e.g. ./dev.ts

2. Add the following code to the entrypoint file

   import { patchSvelteKit, startDevServer } from '@eslym/sveltekit-adapter-bun';
   
   await patchSvelteKit();
   await startDevServer();
   

3. run bun dev.ts

The patchSvelteKit function will patch the sveltekit using bun patch to let it get the original Request object from bun and pass it to the dev server, making Bun.Server#upgrade possible. The startDevServer function will start the dev server with websocket support.

The patchSvelteKit will not impact anything in production build, since the production build will not involve @sveltejs/kit/node unless you are using it in your code.

[!IMPORTANT] This dev server uses bun's internal stuff, so it might break in the future bun version, but the production build will not be affected.

Use the websocket

// ./src/app.d.ts
// for the type checking

import type { AdapterPlatform } from '@eslym/sveltekit-adapter-bun';

// See https://kit.svelte.dev/docs/types#app
// for information about these interfaces
declare global {
    namespace App {
        // interface Error {}
        // interface Locals {}
        // interface PageData {}
        // interface PageState {}
        interface Platform extends AdapterPlatform {}
    }
}

// ./src/routes/echo/+server.ts

export async function GET({ platform }) {
    // can mark any response for upgrade, if the upgrade failed, the response will be sent as is
    return platform!.markForUpgrade(
        new Response('Websocket Requried', {
            status: 400
        }),
        {
            message(ws, message) {
                ws.send(message);
            }
        }
    );
}