fix: match Cache-Control no-transform directive case-insensitively

HISTORY.md

@@ -1,3 +1,8 @@
+unreleased
+==========
+
+  * Match `Cache-Control: no-transform` directive case-insensitively
+
 1.8.1 / 2025-07-17
 ==========
 

index.js

@@ -40,7 +40,7 @@ var hasBrotliSupport = 'createBrotliCompress' in zlib
  * Module variables.
  * @private
  */
-var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
+var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/i
 var SUPPORTED_ENCODING = hasBrotliSupport ? ['br', 'gzip', 'deflate', 'identity'] : ['gzip', 'deflate', 'identity']
 var PREFERRED_ENCODING = hasBrotliSupport ? ['br', 'gzip'] : ['gzip']
 

test/compression.js

@@ -706,6 +706,23 @@ describe('compression()', function () {
         .expect(200, 'hello, world', done)
     })
 
+    ;['No-Transform', 'NO-TRANSFORM', 'public, No-Transform, max-age=60'].forEach(function (value) {
+      it('should not compress response when "Cache-Control: ' + value + '"', function (done) {
+        var server = createServer({ threshold: 0 }, function (req, res) {
+          res.setHeader('Cache-Control', value)
+          res.setHeader('Content-Type', 'text/plain')
+          res.end('hello, world')
+        })
+
+        request(server)
+          .get('/')
+          .set('Accept-Encoding', 'gzip')
+          .expect('Cache-Control', value)
+          .expect(shouldNotHaveHeader('Content-Encoding'))
+          .expect(200, 'hello, world', done)
+      })
+    })
+
     it('should not set Vary headerh', function (done) {
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Cache-Control', 'no-transform')