feat(serve-static): add precompressed option

src/serve-static.ts

@@ -11,11 +11,18 @@ export type ServeStaticOptions<E extends Env = Env> = {
   root?: string
   path?: string
   index?: string // default is 'index.html'
+  precompressed?: boolean
   rewriteRequestPath?: (path: string) => string
   onFound?: (path: string, c: Context<E>) => void | Promise<void>
   onNotFound?: (path: string, c: Context<E>) => void | Promise<void>
 }
 
+const ENCODINGS = {
+  br: '.br',
+  zstd: '.zst',
+  gzip: '.gz',
+} as const
+
 const createStreamBody = (stream: ReadStream) => {
   const body = new ReadableStream({
     start(controller) {
@@ -95,6 +102,30 @@ export const serveStatic = (options: ServeStaticOptions = { root: '' }): Middlew
       c.header('Content-Type', mimeType)
     }
 
+    if (options.precompressed) {
+      const acceptEncodings =
+        c.req
+          .header('Accept-Encoding')
+          ?.split(',')
+          .map((encoding) => encoding.trim())
+          .filter((encoding): encoding is keyof typeof ENCODINGS =>
+            Object.hasOwn(ENCODINGS, encoding)
+          )
+          .sort((a, b) => Object.keys(ENCODINGS).indexOf(a) - Object.keys(ENCODINGS).indexOf(b)) ??
+        []
+
+      for (const encoding of acceptEncodings) {
+        const precompressedStats = getStats(path + ENCODINGS[encoding])
+        if (precompressedStats) {
+          c.header('Content-Encoding', encoding)
+          c.header('Vary', 'Accept-Encoding', { append: true })
+          stats = precompressedStats
+          path = path + ENCODINGS[encoding]
+          break
+        }
+      }
+    }
+
     const size = stats.size
 
     if (c.req.method == 'HEAD' || c.req.method == 'OPTIONS') {

test/assets/static-with-precompressed/hello.txt

@@ -0,0 +1 @@
+Hello Not Compressed

test/assets/static-with-precompressed/hello.txt.br

@@ -0,0 +1 @@
+Hello br Compressed

test/assets/static-with-precompressed/hello.txt.zst

@@ -0,0 +1 @@
+Hello zstd Compressed

test/serve-static.test.ts

@@ -35,6 +35,14 @@ describe('Serve Static Middleware', () => {
     })
   )
 
+  app.use(
+    '/static-with-precompressed/*',
+    serveStatic({
+      root: './test/assets',
+      precompressed: true,
+    })
+  )
+
   const server = createAdaptorServer(app)
 
   it('Should return index.html', async () => {
@@ -149,4 +157,42 @@ describe('Serve Static Middleware', () => {
     expect(res.status).toBe(200)
     expect(res.text).toBe('Extensionless')
   })
+
+  it('Should return a pre-compressed zstd response - /static-with-precompressed/hello.txt', async () => {
+    // Check if it returns a normal response
+    let res = await request(server).get('/static-with-precompressed/hello.txt')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-length']).toBe('20')
+    expect(res.text).toBe('Hello Not Compressed')
+
+    res = await request(server)
+      .get('/static-with-precompressed/hello.txt')
+      .set('Accept-Encoding', 'zstd')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-length']).toBe('21')
+    expect(res.headers['content-encoding']).toBe('zstd')
+    expect(res.headers['vary']).toBe('Accept-Encoding')
+    expect(res.text).toBe('Hello zstd Compressed')
+  })
+
+  it('Should return a pre-compressed brotli response - /static-with-precompressed/hello.txt', async () => {
+    const res = await request(server)
+      .get('/static-with-precompressed/hello.txt')
+      .set('Accept-Encoding', 'wompwomp, gzip, br, deflate, zstd')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-length']).toBe('19')
+    expect(res.headers['content-encoding']).toBe('br')
+    expect(res.headers['vary']).toBe('Accept-Encoding')
+    expect(res.text).toBe('Hello br Compressed')
+  })
+
+  it('Should not return a pre-compressed response - /static-with-precompressed/hello.txt', async () => {
+    const res = await request(server)
+      .get('/static-with-precompressed/hello.txt')
+      .set('Accept-Encoding', 'wompwomp, unknown')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-encoding']).toBeUndefined()
+    expect(res.headers['vary']).toBeUndefined()
+    expect(res.text).toBe('Hello Not Compressed')
+  })
 })