From 1421934fde119e20cee8490a5fb57f8db825b9c0 Mon Sep 17 00:00:00 2001
From: Hakim El Hattab
Date: Thu, 10 Oct 2013 09:20:54 -0400
Subject: code style

---
 js/reveal.js | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

(limited to 'js/reveal.js')

diff --git a/js/reveal.js b/js/reveal.js
index 600a763..e6368d6 100644
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -615,15 +615,20 @@ var Reveal = (function(){
 
 		if( config.focusBodyOnPageVisiblityChange ) {
 			var visibilityChange;
-			if ('hidden' in document) {
+
+			if( 'hidden' in document ) {
 				visibilityChange = 'visibilitychange';
-			} else if ('msHidden' in document) {
+			}
+			else if( 'msHidden' in document ) {
 				visibilityChange = 'msvisibilitychange';
-			} else if ('webkitHidden' in document) {
+			}
+			else if( 'webkitHidden' in document ) {
 				visibilityChange = 'webkitvisibilitychange';
 			}
 
-			document.addEventListener(visibilityChange, onPageVisibilityChange, false);
+			if( visibilityChange ) {
+				document.addEventListener( visibilityChange, onPageVisibilityChange, false );
+			}
 		}
 
 		[ 'touchstart', 'click' ].forEach( function( eventName ) {
-- 
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