feat: add default option (#191)

* add test for default encoding

* add functionality

* support *

* add docs

* fix logic

* change defaultEncoding to enforceEnconding

* sort conditional

HISTORY.md

@@ -1,10 +1,10 @@
 unreleased
 ==========
   * Use `res.headersSent` when available
+  * Add the enforceEncoding option for requests without `Accept-Encoding` header
 
 1.7.5 / 2024-10-31
 ==========
-
   * deps: Replace accepts with negotiator@~0.6.4
     - Add preference option
   * deps: bytes@3.1.2

README.md

@@ -139,6 +139,12 @@ The default value is `zlib.Z_DEFAULT_WINDOWBITS`, or `15`.
 See [Node.js documentation](http://nodejs.org/api/zlib.html#zlib_memory_usage_tuning)
 regarding the usage.
 
+##### enforceEncoding
+
+This is the default encoding to use when the client does not specify an encoding in the request's [Accept-Encoding](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding) header.
+
+The default value is `identity`.
+
 #### .filter
 
 The default `filter` function. This is used to construct a custom filter

index.js

@@ -37,6 +37,8 @@ module.exports.filter = shouldCompress
 
 var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
 
+var encodingSupported = ['*', 'gzip', 'deflate', 'identity']
+
 /**
  * Compress response data with gzip / deflate.
  *
@@ -51,6 +53,7 @@ function compression (options) {
   // options
   var filter = opts.filter || shouldCompress
   var threshold = bytes.parse(opts.threshold)
+  var enforceEncoding = opts.enforceEncoding || 'identity'
 
   if (threshold == null) {
     threshold = 1024
@@ -177,6 +180,11 @@ function compression (options) {
       var negotiator = new Negotiator(req)
       var method = negotiator.encoding(['gzip', 'deflate', 'identity'], ['gzip'])
 
+      // if no method is found, use the default encoding
+      if (!req.headers['accept-encoding'] && encodingSupported.indexOf(enforceEncoding) !== -1) {
+        method = enforceEncoding === '*' ? 'gzip' : enforceEncoding
+      }
+
       // negotiation failed
       if (!method || method === 'identity') {
         nocompress('not acceptable')

test/compression.js

@@ -702,6 +702,86 @@ describe('compression()', function () {
         .end()
     })
   })
+
+  describe('enforceEncoding', function () {
+    it('should compress the provided encoding and not the default encoding', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: 'deflate' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'gzip')
+        .expect('Content-Encoding', 'gzip')
+        .expect(200, 'hello, world', done)
+    })
+
+    it('should not compress when enforceEncoding is identity', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: 'identity' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', '')
+        .expect(shouldNotHaveHeader('Content-Encoding'))
+        .expect(200, 'hello, world', done)
+    })
+
+    it('should compress when enforceEncoding is gzip', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: 'gzip' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', '')
+        .expect('Content-Encoding', 'gzip')
+        .expect(200, 'hello, world', done)
+    })
+
+    it('should compress when enforceEncoding is deflate', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: 'deflate' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', '')
+        .expect('Content-Encoding', 'deflate')
+        .expect(200, 'hello, world', done)
+    })
+
+    it('should not compress when enforceEncoding is unknown', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: 'bogus' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', '')
+        .expect(shouldNotHaveHeader('Content-Encoding'))
+        .expect(200, 'hello, world', done)
+    })
+
+    it('should be gzip if no accept-encoding is sent when enforceEncoding is *', function (done) {
+      var server = createServer({ threshold: 0, enforceEncoding: '*' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', '')
+        .expect('Content-Encoding', 'gzip')
+        .expect(200, 'hello, world', done)
+    })
+  })
 })
 
 function createServer (opts, fn) {