From ff5e64e4311bfecc6d15c520c16add2247a2bbc0 Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Thu, 8 Jun 2017 12:51:07 +0200
Subject: [PATCH] no need to double-check second half of a surrogate pair

---
 notebook/static/base/js/utils.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/notebook/static/base/js/utils.js b/notebook/static/base/js/utils.js
index 73551b61c..b24f0aa81 100644
--- a/notebook/static/base/js/utils.js
+++ b/notebook/static/base/js/utils.js
@@ -1031,7 +1031,8 @@ define([
             if (char_code >= 0xD800 && char_code <= 0xDBFF) {
                 var next_char_code = text.charCodeAt(i+1);
                 if (next_char_code >= 0xDC00 && next_char_code <= 0xDFFF) {
-                    char_idx -= 1;
+                    char_idx--;
+                    i++;
                 }
             }
         }
@@ -1046,7 +1047,8 @@ define([
             if (char_code >= 0xD800 && char_code <= 0xDBFF) {
                 var next_char_code = text.charCodeAt(i+1);
                 if (next_char_code >= 0xDC00 && next_char_code <= 0xDFFF) {
-                    js_idx += 1;
+                    js_idx++;
+                    i++;
                 }
             }
         }