WebSocket Adapter for TanStack Start

start-adapter.ts

import { json } from '@tanstack/react-start'
import { getEvent, type ServerRouteMethodsRecord } from '@tanstack/react-start/server'
import createNodeAdapter, { type NodeOptions as NodeAdapterOptions } from 'crossws/adapters/node'

/**
 * Adapter for TanStack Start and `crossws`.
 *
 * @see https://tanstack.com/start/latest/docs/framework/react/server-routes
 * @see https://nitro.build/guide/websocket
 *
 * @example
 *
 * ```
 * import { createServerFileRoute } from '@tanstack/react-start/server'
 * import { createWebSocketHandler } from '...'
 *
 * export const ServerRoute = createServerFileRoute('/api/ws').methods(createWebSocketHandler({
 *   serverOptions: {
 *     // ...
 *   },
 *   hooks: {
 *     open: () => {
 *       // ...
 *     },
 *     message: () => {
 *       // ...
 *     },
 *     error: : () => {
 *       // ...
 *     },
 *     close: : () => {
 *       // ...
 *     },
 *   }
 * }))
 * ```
 */
export function createWebSocketHandler(options: NodeAdapterOptions): ServerRouteMethodsRecord<any, any, any> {
  const nodeAdapter = createNodeAdapter(options)

  const handler = async () => {
    try {
      const event = getEvent()
      if (event.node.req.headers.upgrade === 'websocket') {
        const { req } = event.node
        const { socket } = req
        if (socket) {
          await nodeAdapter.handleUpgrade(req, socket, Buffer.from([]))
          return
        }
      }

      return json({ message: 'This is a WebSocket endpoint.' }, { status: 400, statusText: 'Bad Request' })
    } catch (error: any) {
      const message = error.message ?? 'An unknown error occurred.'
      return json({ message }, { status: 500, statusText: 'Internal Server Error' })
    }
  }

  return {
    GET: handler,
    POST: handler
  }
}