From d912d1406cf06729edfd6af9da6cdaa5eed49e17 Mon Sep 17 00:00:00 2001
From: Martin Ratinaud <martinratinaud@gmail.com>
Date: Thu, 10 Sep 2015 15:51:29 +0200
Subject: [PATCH] Add guard on classList function if element does not exist
 anymore

---
 nprogress.js | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/nprogress.js b/nprogress.js
index b23b300..ef69871 100644
--- a/nprogress.js
+++ b/nprogress.js
@@ -83,16 +83,16 @@
 
       if (n === 1) {
         // Fade out
-        css(progress, { 
-          transition: 'none', 
-          opacity: 1 
+        css(progress, {
+          transition: 'none',
+          opacity: 1
         });
         progress.offsetWidth; /* Repaint */
 
         setTimeout(function() {
-          css(progress, { 
-            transition: 'all ' + speed + 'ms linear', 
-            opacity: 0 
+          css(progress, {
+            transition: 'all ' + speed + 'ms linear',
+            opacity: 0
           });
           setTimeout(function() {
             NProgress.remove();
@@ -220,7 +220,7 @@
     if (NProgress.isRendered()) return document.getElementById('nprogress');
 
     addClass(document.documentElement, 'nprogress-busy');
-    
+
     var progress = document.createElement('div');
     progress.id = 'nprogress';
     progress.innerHTML = Settings.template;
@@ -229,7 +229,7 @@
         perc     = fromStart ? '-100' : toBarPerc(NProgress.status || 0),
         parent   = document.querySelector(Settings.parent),
         spinner;
-    
+
     css(bar, {
       transition: 'all 0 linear',
       transform: 'translate3d(' + perc + '%,0,0)'
@@ -340,7 +340,7 @@
 
   var queue = (function() {
     var pending = [];
-    
+
     function next() {
       var fn = pending.shift();
       if (fn) {
@@ -355,10 +355,10 @@
   })();
 
   /**
-   * (Internal) Applies css properties to an element, similar to the jQuery 
+   * (Internal) Applies css properties to an element, similar to the jQuery
    * css method.
    *
-   * While this helper does assist with vendor prefixed property names, it 
+   * While this helper does assist with vendor prefixed property names, it
    * does not perform any manipulation of values prior to setting styles.
    */
 
@@ -399,7 +399,7 @@
 
     return function(element, properties) {
       var args = arguments,
-          prop, 
+          prop,
           value;
 
       if (args.length == 2) {
@@ -430,7 +430,7 @@
     var oldList = classList(element),
         newList = oldList + name;
 
-    if (hasClass(oldList, name)) return; 
+    if (hasClass(oldList, name)) return;
 
     // Trim the opening space.
     element.className = newList.substring(1);
@@ -454,13 +454,13 @@
   }
 
   /**
-   * (Internal) Gets a space separated list of the class names on the element. 
-   * The list is wrapped with a single space on each end to facilitate finding 
+   * (Internal) Gets a space separated list of the class names on the element.
+   * The list is wrapped with a single space on each end to facilitate finding
    * matches within the list.
    */
 
   function classList(element) {
-    return (' ' + (element.className || '') + ' ').replace(/\s+/gi, ' ');
+    return (' ' + (element && element.className || '') + ' ').replace(/\s+/gi, ' ');
   }
 
   /**
@@ -473,4 +473,3 @@
 
   return NProgress;
 });
-