use negotiator

encoding_negotiator.js

@@ -1,77 +1,30 @@
 var zlib = require('zlib')
+var Negotiator = require('negotiator')
 
 /**
  * @const
  * whether current node version has brotli support
  */
 var hasBrotliSupport = 'createBrotliCompress' in zlib
 
-var supportedEncodings = hasBrotliSupport
-  ? ['br', 'gzip', 'deflate', 'identity']
-  : ['gzip', 'deflate', 'identity']
+function negotiateEncoding (req, encodings_) {
+  var negotiator = new Negotiator(req)
+  var encodings = encodings_
 
-var preferredEncodings = hasBrotliSupport
-  ? ['br', 'gzip']
-  : ['gzip']
-
-function negotiateEncoding (header) {
-  header = header || ''
-
-  var insts = header.split(',')
-  var decoded = []
-
-  for (var i = 0; i < insts.length; i++) {
-    var inst = insts[i].match(/^\s*?([^\s;]+?)\s*?(?:;(.*))?$/)
-    if (!inst) continue
-
-    var encoding = inst[1]
-    if (supportedEncodings.indexOf(encoding) === -1) {
-      continue
+  // support flattened arguments
+  if (encodings && !Array.isArray(encodings)) {
+    encodings = new Array(arguments.length)
+    for (var i = 0; i < encodings.length; i++) {
+      encodings[i] = arguments[i]
     }
-
-    var q = 1
-    if (inst[2]) {
-      var params = inst[2].split(';')
-      for (var j = 0; j < params.length; j++) {
-        var p = params[j].trim().split('=')
-        if (p[0] === 'q') {
-          q = parseFloat(p[1])
-          break
-        }
-      }
-    }
-
-    if (q < 0 || q > 1) { // invalid
-      continue
-    }
-
-    decoded.push({ encoding: encoding, q: q, i: i })
   }
 
-  decoded.sort(function (a, b) {
-    if (a.q !== b.q) {
-      return b.q - a.q // higher quality first
-    }
-
-    var aPreferred = preferredEncodings.indexOf(a.encoding)
-    var bPreferred = preferredEncodings.indexOf(b.encoding)
-
-    if (aPreferred === -1 && bPreferred === -1) {
-      return a.i - b.i // consider the original order
-    }
-
-    if (aPreferred !== -1 && bPreferred !== -1) {
-      return aPreferred - bPreferred // consider the preferred order
-    }
-
-    return aPreferred === -1 ? 1 : -1 // preferred first
-  })
-
-  if (decoded.length > 0) {
-    return decoded[0].encoding
+  // no encodings, return all requested encodings
+  if (!encodings || encodings.length === 0) {
+    return negotiator.encodings()
   }
 
-  return null
+  return negotiator.encodings(encodings, hasBrotliSupport ? ['br'] : ['gzip'])[0] || false
 }
 
 module.exports.hasBrotliSupport = hasBrotliSupport

index.js

@@ -189,10 +189,15 @@ function compression (options) {
       }
 
       // compression method
-      var method = negotiateEncoding(req.headers['accept-encoding']) || 'identity'
+      var method = negotiateEncoding(req, ['br', 'gzip', 'deflate', 'identity'])
+
+      // we really don't prefer deflate
+      if (method === 'deflate' && negotiateEncoding(req, ['gzip'])) {
+        method = negotiateEncoding(req, ['br', 'gzip', 'identity'])
+      }
 
       // negotiation failed
-      if (method === 'identity') {
+      if (!method || method === 'identity') {
         nocompress('not acceptable')
         return
       }

package.json

@@ -9,7 +9,7 @@
   "license": "MIT",
   "repository": "expressjs/compression",
   "dependencies": {
-    "accepts": "~1.3.8",
+    "negotiator": "0.6.4",
     "bytes": "3.0.0",
     "compressible": "~2.0.18",
     "debug": "2.6.9",

test/compression.js

@@ -14,6 +14,7 @@ var compression = require('..')
  * whether current node version has brotli support
  */
 var hasBrotliSupport = 'createBrotliCompress' in zlib
+var brotlit = hasBrotliSupport ? it : it.skip
 
 describe('compression()', function () {
   it('should skip HEAD', function (done) {
@@ -472,7 +473,6 @@ 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')
@@ -487,7 +487,6 @@ describe('compression()', function () {
   })
 
   describe('when "Accept-Encoding: br" and passing compression level', function () {
-    var brotlit = hasBrotliSupport ? it : it.skip
     brotlit('should respond with br', function (done) {
       var params = {}
       params[zlib.constants.BROTLI_PARAM_QUALITY] = 11
@@ -548,7 +547,6 @@ describe('compression()', function () {
   })
 
   describe('when "Accept-Encoding: deflate, gzip, 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')
@@ -563,7 +561,6 @@ describe('compression()', function () {
   })
 
   describe('when "Accept-Encoding: gzip;q=1, br;q=0.3"', function () {
-    var brotlit = hasBrotliSupport ? it : it.skip
     brotlit('should respond with gzip', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
@@ -578,7 +575,6 @@ describe('compression()', function () {
   })
 
   describe('when "Accept-Encoding: gzip, br;q=0.8"', function () {
-    var brotlit = hasBrotliSupport ? it : it.skip
     brotlit('should respond with gzip', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
@@ -593,7 +589,6 @@ describe('compression()', function () {
   })
 
   describe('when "Accept-Encoding: gzip;q=0.001"', function () {
-    var brotlit = hasBrotliSupport ? it : it.skip
     brotlit('should respond with gzip', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
@@ -608,7 +603,6 @@ 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')
@@ -760,7 +754,6 @@ describe('compression()', function () {
         .end()
     })
 
-    var brotlit = hasBrotliSupport ? it : it.skip
     brotlit('should flush small chunks for brotli', function (done) {
       var chunks = 0
       var next