From 80c55e4f30b720243ea220cb33ff33ebad761e76 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Thu, 15 Nov 2018 23:40:48 +0000
Subject: [PATCH] Repair error in Decoder.nextbytes

---
 implementations/javascript/package.json       | 2 +-
 implementations/javascript/src/codec.js       | 2 +-
 implementations/javascript/test/test-codec.js | 8 ++++++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/implementations/javascript/package.json b/implementations/javascript/package.json
index 7cab7ad..692d070 100644
--- a/implementations/javascript/package.json
+++ b/implementations/javascript/package.json
@@ -1,6 +1,6 @@
 {
   "name": "preserves",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "description": "Experimental data serialization format",
   "homepage": "https://gitlab.com/tonyg/preserves",
   "license": "MIT",
diff --git a/implementations/javascript/src/codec.js b/implementations/javascript/src/codec.js
index 4f08317..25595c1 100644
--- a/implementations/javascript/src/codec.js
+++ b/implementations/javascript/src/codec.js
@@ -56,7 +56,7 @@ class Decoder {
     const start = this.advance(n);
     if (this.index > this.packet.length) throw new DecodeError("Short packet");
     // ^ NOTE: greater-than, not greater-than-or-equal-to.
-    return new DataView(this.packet.buffer, start, n);
+    return new DataView(this.packet.buffer, this.packet.byteOffset + start, n);
   }
 
   nextvalues(n) {
diff --git a/implementations/javascript/test/test-codec.js b/implementations/javascript/test/test-codec.js
index 3b3c74e..0d5f93c 100644
--- a/implementations/javascript/test/test-codec.js
+++ b/implementations/javascript/test/test-codec.js
@@ -141,3 +141,11 @@ describe('hex samples', () => {
     });
   });
 });
+
+describe('parsing from subarray', () => {
+  it('should maintain alignment of nextbytes', () => {
+    const u = Uint8Array.of(57, 57, 57, 57, 83, 51, 51, 51);
+    const bs = Bytes.from(u.subarray(4));
+    expect(new Decoder(bs).next()).to.equal("333");
+  });
+});