feat: Introduce Service Worker Adapter

jsr.json

@@ -69,6 +69,7 @@
     "./vercel": "./src/adapter/vercel/index.ts",
     "./netlify": "./src/adapter/netlify/index.ts",
     "./lambda-edge": "./src/adapter/lambda-edge/index.ts",
+    "./service-worker": "./src/adapter/service-worker/index.ts",
     "./testing": "./src/helper/testing/index.ts",
     "./dev": "./src/helper/dev/index.ts",
     "./ws": "./src/helper/websocket/index.ts",

package.json

@@ -333,6 +333,11 @@
       "import": "./dist/adapter/lambda-edge/index.js",
       "require": "./dist/cjs/adapter/lambda-edge/index.js"
     },
+    "./service-worker": {
+      "types": "./dist/types/adapter/service-worker/index.d.ts",
+      "import": "./dist/adapter/service-worker/index.js",
+      "require": "./dist/cjs/adapter/service-worker/index.js"
+    },
     "./testing": {
       "types": "./dist/types/helper/testing/index.d.ts",
       "import": "./dist/helper/testing/index.js",
@@ -527,6 +532,9 @@
       "lambda-edge": [
         "./dist/types/adapter/lambda-edge"
       ],
+      "service-worker": [
+        "./dist/types/adapter/service-worker"
+      ],
       "testing": [
         "./dist/types/helper/testing"
       ],

src/adapter/service-worker/handler.test.ts

@@ -0,0 +1,57 @@
+import { Hono } from '../../hono'
+import { handle } from './handler'
+import type { FetchEvent } from './types'
+
+describe('handle', () => {
+  it('Success to fetch', async () => {
+    const app = new Hono()
+    app.get('/', (c) => {
+      return c.json({ hello: 'world' })
+    })
+    const handler = handle(app)
+    const json = await new Promise<Response>((resolve) => {
+      handler({
+        request: new Request('http://localhost/'),
+        respondWith(res) {
+          resolve(res)
+        },
+      } as FetchEvent)
+    }).then((res) => res.json())
+    expect(json).toStrictEqual({ hello: 'world' })
+  })
+  it('Fallback 404', async () => {
+    const app = new Hono()
+    const handler = handle(app, {
+      async fetch() {
+        return new Response('hello world')
+      },
+    })
+    const text = await new Promise<Response>((resolve) => {
+      handler({
+        request: new Request('http://localhost/'),
+        respondWith(res) {
+          resolve(res)
+        },
+      } as FetchEvent)
+    }).then((res) => res.text())
+    expect(text).toBe('hello world')
+  })
+  it('Do not fallback 404 when fetch is undefined', async () => {
+    const app = new Hono()
+    app.get('/', (c) => c.text('Not found', 404))
+    const handler = handle(app, {
+      fetch: undefined,
+    })
+    const result = await new Promise<Response>((resolve) =>
+      handler({
+        request: new Request('https://localhost/'),
+        respondWith(r) {
+          resolve(r)
+        },
+      } as FetchEvent)
+    )
+
+    expect(result.status).toBe(404)
+    expect(await result.text()).toBe('Not found')
+  })
+})

src/adapter/service-worker/handler.ts

@@ -0,0 +1,33 @@
+/**
+ * Handler for Service Worker
+ * @module
+ */
+
+import type { Hono } from '../../hono'
+import type { FetchEvent } from './types'
+
+type Handler = (evt: FetchEvent) => void
+
+/**
+ * Adapter for Service Worker
+ */
+export const handle = (
+  app: Hono,
+  opts: {
+    fetch?: typeof fetch
+  } = {
+    fetch: fetch,
+  }
+): Handler => {
+  return (evt) => {
+    evt.respondWith(
+      (async () => {
+        const res = await app.fetch(evt.request)
+        if (opts.fetch && res.status === 404) {
+          return await opts.fetch(evt.request)
+        }
+        return res
+      })()
+    )
+  }
+}

src/adapter/service-worker/index.ts

@@ -0,0 +1,5 @@
+/**
+ * Cloudflare Workers Adapter for Hono.
+ * @module
+ */
+export { handle } from './handler'

src/adapter/service-worker/types.ts

@@ -0,0 +1,14 @@
+interface ExtendableEvent extends Event {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  waitUntil(f: Promise<any>): void
+}
+
+export interface FetchEvent extends ExtendableEvent {
+  readonly clientId: string
+  readonly handled: Promise<undefined>
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  readonly preloadResponse: Promise<any>
+  readonly request: Request
+  readonly resultingClientId: string
+  respondWith(r: Response | PromiseLike<Response>): void
+}