From 5f51206e5a01a27bd14f4951ffcc182002fe343f Mon Sep 17 00:00:00 2001
From: Ilya Kantor <iliakan@gmail.com>
Date: Mon, 16 Jul 2018 11:47:59 +0300
Subject: [PATCH] minor

---
 2-ui/1-document/11-coordinates/head.html | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/2-ui/1-document/11-coordinates/head.html b/2-ui/1-document/11-coordinates/head.html
index efc6cd1c..0914f7f8 100644
--- a/2-ui/1-document/11-coordinates/head.html
+++ b/2-ui/1-document/11-coordinates/head.html
@@ -1,7 +1,11 @@
 <script>
 document.addEventListener('DOMContentLoaded', function() {
 
-  document.getElementById('coords-show-mark').onclick = function() {
+let elem = document.getElementById('coords-show-mark');
+
+// no elem in ebook mode
+if (elem) {
+  elem.onclick = function() {
     let elem = document.getElementById("coords-show-mark");
 
     function createMessageUnder(elem, text) {
@@ -21,6 +25,7 @@ document.addEventListener('DOMContentLoaded', function() {
     document.body.append(message);
     setTimeout(() => message.remove(), 5000);
   }
+}
 
 });