From ea9b207b0ba881a70f81cc5b1ab35e7fc9b5a844 Mon Sep 17 00:00:00 2001
From: Project Nayuki <me@nayuki.io>
Date: Sat, 23 Jun 2018 16:21:04 +0000
Subject: [PATCH] Fixed JavaScript UTF-16 logic to handle a rare erroneous edge
 case.

---
 javascript/qrcodegen-demo.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/javascript/qrcodegen-demo.js b/javascript/qrcodegen-demo.js
index 2712985..191cc9a 100644
--- a/javascript/qrcodegen-demo.js
+++ b/javascript/qrcodegen-demo.js
@@ -109,7 +109,7 @@ function redrawQrCode() {
 			var c = str.charCodeAt(i);
 			if (c < 0xD800 || c >= 0xE000)
 				continue;
-			else if (0xD800 <= c && c < 0xDC00) {  // High surrogate
+			else if (0xD800 <= c && c < 0xDC00 && i + 1 < str.length) {  // High surrogate
 				i++;
 				var d = str.charCodeAt(i);
 				if (0xDC00 <= d && d < 0xE000)  // Low surrogate