From 174a1d12b68dfbd531a572eaaea0937491b36f55 Mon Sep 17 00:00:00 2001
From: Alex Kocharin <alex@kocharin.ru>
Date: Fri, 10 Jun 2022 20:44:21 +0300
Subject: [PATCH] Ensure backward compatibility for `headers.extra`

---
 lib/zlib/deflate.js   | 5 ++++-
 test/gzip_specials.js | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/zlib/deflate.js b/lib/zlib/deflate.js
index cefd2cf..00e056e 100644
--- a/lib/zlib/deflate.js
+++ b/lib/zlib/deflate.js
@@ -1738,9 +1738,12 @@ const deflate = (strm, flush) => {
         beg = 0;
         left -= copy;
       }
+      // JS specific: s.gzhead.extra may be TypedArray or Array for backward compatibility
+      //              TypedArray.slice and TypedArray.from don't exist in IE10-IE11
+      let gzhead_extra = new Uint8Array(s.gzhead.extra);
       // zmemcpy(s->pending_buf + s->pending,
       //     s->gzhead->extra + s->gzindex, left);
-      s.pending_buf.set(s.gzhead.extra.subarray(s.gzindex, s.gzindex + left), s.pending);
+      s.pending_buf.set(gzhead_extra.subarray(s.gzindex, s.gzindex + left), s.pending);
       s.pending += left;
       //--- HCRC_UPDATE(beg) ---//
       if (s.gzhead.hcrc && s.pending > beg) {
diff --git a/test/gzip_specials.js b/test/gzip_specials.js
index fc2f6b7..db2bd54 100644
--- a/test/gzip_specials.js
+++ b/test/gzip_specials.js
@@ -38,7 +38,7 @@ describe('Gzip special cases', () => {
         os: 15,
         name: 'test name',
         comment: 'test comment',
-        extra: new Uint8Array([ 4, 5, 6 ])
+        extra: [ 4, 5, 6 ]
       }
     });
     deflator.push(data, true);