From 2bcc3175da7cd24a78c493bd2fa1f6d8e06336bb Mon Sep 17 00:00:00 2001
From: youdie006 <youdie006@users.noreply.github.com>
Date: Fri, 2 Oct 2026 18:34:37 +0900
Subject: [PATCH] fix(convert): decode JIS X 0212 0x2237 to a single character

EUCJPToUTF8() and JISToUTF8() always wrote at least two bytes for a JIS
X 0212 table value, so 0x2237, which maps to ~, decoded to a NUL
followed by ~.
---
 src/encoding-convert.js |  8 ++++++--
 tests/test.js           | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/encoding-convert.js b/src/encoding-convert.js
index bcdd154..83d5833 100644
--- a/src/encoding-convert.js
+++ b/src/encoding-convert.js
@@ -511,7 +511,9 @@ function EUCJPToUTF8(data) {
       if (utf8 === void 0) {
         results[results.length] = config.FALLBACK_CHARACTER;
       } else {
-        if (utf8 < 0xFFFF) {
+        if (utf8 < 0x80) {
+          results[results.length] = utf8;
+        } else if (utf8 < 0xFFFF) {
           results[results.length] = utf8 >> 8 & 0xFF;
           results[results.length] = utf8 & 0xFF;
         } else {
@@ -609,7 +611,9 @@ function JISToUTF8(data) {
       if (utf8 === void 0) {
         results[results.length] = config.FALLBACK_CHARACTER;
       } else {
-        if (utf8 < 0xFFFF) {
+        if (utf8 < 0x80) {
+          results[results.length] = utf8;
+        } else if (utf8 < 0xFFFF) {
           results[results.length] = utf8 >> 8 & 0xFF;
           results[results.length] = utf8 & 0xFF;
         } else {
diff --git a/tests/test.js b/tests/test.js
index f55e487..0440ab0 100644
--- a/tests/test.js
+++ b/tests/test.js
@@ -1249,6 +1249,17 @@ describe('encoding', function() {
       assert.equal(decoded, '?');
     });
 
+    it('JIS X 0212 code point mapped to ASCII', function() {
+      // JIS X 0212 0x2237 maps to U+007E, a single UTF-8 byte.
+      var eucjp = [0x8F, 0xA2, 0xB7];
+      var jis = [0x1B, 0x24, 0x28, 0x44, 0x22, 0x37, 0x1B, 0x28, 0x42];
+
+      assert.deepEqual(encoding.convert(eucjp, 'UTF8', 'EUCJP'), [0x7E]);
+      assert.deepEqual(encoding.convert(eucjp, 'UNICODE', 'EUCJP'), [0x7E]);
+      assert.deepEqual(encoding.convert(jis, 'UTF8', 'JIS'), [0x7E]);
+      assert.deepEqual(encoding.convert(jis, 'UNICODE', 'JIS'), [0x7E]);
+    });
+
     it('SJIS invalid trail byte 0x7F', function() {
       var invalidSjisCode = [0x81, 0x7F];
       var validSjisCode = [0x81, 0x7E];