Added support for brotli ('br') content-encoding

README.md

@@ -11,6 +11,9 @@ The following compression codings are supported:
 
   - deflate
   - gzip
+  - br (brotli)
+
+**Note** Brotli provides better and faster compression then gzip or deflate, but is supported only since Node.js versions v11.7.0 and v10.16.0.
 
 ## Install
 
@@ -46,6 +49,9 @@ as compressing will transform the body.
 those listed below, [zlib](http://nodejs.org/api/zlib.html) options may be
 passed in to the options object.
 
+As for *brotli*, a default is set to compression level 4, unless  
+[anything else is specified](https://nodejs.org/api/zlib.html#zlib_class_brotlioptions).
+
 ##### chunkSize
 
 The default value is `zlib.Z_DEFAULT_CHUNK`, or `16384`.

index.js

@@ -19,6 +19,7 @@ var Buffer = require('safe-buffer').Buffer
 var bytes = require('bytes')
 var compressible = require('compressible')
 var debug = require('debug')('compression')
+var objectAssign = require('object-assign')
 var onHeaders = require('on-headers')
 var vary = require('vary')
 var zlib = require('zlib')
@@ -37,6 +38,24 @@ module.exports.filter = shouldCompress
 
 var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
 
+/**
+ * @const
+ * whether current node version has brotli support
+ */
+var hasBrotliSupport = 'brotli' in process.versions
+
+var supportedEncodings = hasBrotliSupport
+  ? ['gzip', 'deflate', 'br', 'identity']
+  : ['gzip', 'deflate', 'identity']
+
+var supportedCompressionsNoDeflate = hasBrotliSupport
+  ? ['gzip', 'br']
+  : ['gzip']
+
+var supportedEncodingsNoDeflate = hasBrotliSupport
+  ? ['gzip', 'br', 'identity']
+  : ['gzip', 'identity']
+
 /**
  * Compress response data with gzip / deflate.
  *
@@ -48,6 +67,12 @@ var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
 function compression (options) {
   var opts = options || {}
 
+  if (hasBrotliSupport && opts.params === undefined) {
+    opts = objectAssign({}, opts)
+    opts.params = {}
+    opts.params[zlib.constants.BROTLI_PARAM_QUALITY] = 4
+  }
+
   // options
   var filter = opts.filter || shouldCompress
   var threshold = bytes.parse(opts.threshold)
@@ -175,11 +200,11 @@ function compression (options) {
 
       // compression method
       var accept = accepts(req)
-      var method = accept.encoding(['gzip', 'deflate', 'identity'])
+      var method = accept.encoding(supportedEncodings)
 
       // we really don't prefer deflate
-      if (method === 'deflate' && accept.encoding(['gzip'])) {
-        method = accept.encoding(['gzip', 'identity'])
+      if (method === 'deflate' && accept.encoding(supportedCompressionsNoDeflate)) {
+        method = accept.encoding(supportedEncodingsNoDeflate)
       }
 
       // negotiation failed
@@ -192,7 +217,9 @@ function compression (options) {
       debug('%s compression', method)
       stream = method === 'gzip'
         ? zlib.createGzip(opts)
-        : zlib.createDeflate(opts)
+        : method === 'br'
+          ? zlib.createBrotliCompress(opts)
+          : zlib.createDeflate(opts)
 
       // add buffered listeners to stream
       addListeners(stream, stream.on, listeners)

package.json

@@ -13,6 +13,7 @@
     "bytes": "3.0.0",
     "compressible": "~2.0.16",
     "debug": "2.6.9",
+    "object-assign": "4.1.1",
     "on-headers": "~1.0.2",
     "safe-buffer": "5.1.2",
     "vary": "~1.1.2"

test/compression.js

@@ -9,6 +9,12 @@ var zlib = require('zlib')
 
 var compression = require('..')
 
+/**
+ * @const
+ * whether current node version has brotli support
+ */
+var hasBrotliSupport = 'brotli' in process.versions
+
 describe('compression()', function () {
   it('should skip HEAD', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
@@ -465,6 +471,21 @@ describe('compression()', function () {
     })
   })
 
+  describe('when "Accept-Encoding: br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
   describe('when "Accept-Encoding: gzip, deflate"', function () {
     it('should respond with gzip', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
@@ -493,6 +514,21 @@ describe('compression()', function () {
     })
   })
 
+  describe('when "Accept-Encoding: deflate, br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'deflate, br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
   describe('when "Cache-Control: no-transform" response header', function () {
     it('should not compress response', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
@@ -631,6 +667,33 @@ describe('compression()', function () {
         .end()
     })
 
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should flush small chunks for brotli', function (done) {
+      var chunks = 0
+      var next
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        next = writeAndFlush(res, 2, Buffer.from('..'))
+        res.setHeader('Content-Type', 'text/plain')
+        next()
+      })
+
+      function onchunk (chunk) {
+        assert.ok(chunks++ < 20)
+        assert.strictEqual(chunk.toString(), '..')
+        next()
+      }
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'br')
+        .request()
+        .on('response', unchunk('br', onchunk, function (err) {
+          if (err) return done(err)
+          server.close(done)
+        }))
+        .end()
+    })
+
     it('should flush small chunks for deflate', function (done) {
       var chunks = 0
       var next
@@ -710,6 +773,9 @@ function unchunk (encoding, onchunk, onend) {
       case 'gzip':
         stream = res.pipe(zlib.createGunzip())
         break
+      case 'br':
+        stream = res.pipe(zlib.createBrotliDecompress())
+        break
     }
 
     stream.on('data', onchunk)