From 7d999509426cfb425cb441a492ec8698aaff3ed9 Mon Sep 17 00:00:00 2001
From: Will Thompson <will@willthompson.co.uk>
Date: Thu, 25 Feb 2016 10:57:04 +0000
Subject: [PATCH] Only setInterval once to animate the loading icon (fixes
 #2888)

(On Chrome, at least,) window.onload() is called once by hand, and once
by the browser. This ends up calling setInterval() twice. When
stopAnimation() is called later, only the second interval is cleared; so
the first one keeps firing forever. Mostly harmless but unnecessary.

Only the first hunk of this patch is really needed, but making
startAnimation() / stopAnimation() idempotent can't hurt.
---
 static/js/pandora.js | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/static/js/pandora.js b/static/js/pandora.js
index d123f47e..cda1e5fe 100644
--- a/static/js/pandora.js
+++ b/static/js/pandora.js
@@ -188,10 +188,14 @@ appPanel
         loadingScreen.appendChild(images.loadingIcon);
 
         // FF3.6 document.body can be undefined here
+        var onloadCalled = false;
         window.onload = function() {
-            document.body.style.margin = 0;
-            document.body.appendChild(loadingScreen);
-            startAnimation();
+            if (!onloadCalled) {
+                onloadCalled = true;
+                document.body.style.margin = 0;
+                document.body.appendChild(loadingScreen);
+                startAnimation();
+            }
         };
         // IE8 does not call onload if already loaded before set
         document.body && window.onload();
@@ -556,6 +560,10 @@ appPanel
     }
 
     function startAnimation() {
+        if (animationInterval !== undefined) {
+            return;
+        }
+
         var css, deg = 0, loadingIcon = document.getElementById('loadingIcon'),
             previousTime = +new Date();
         animationInterval = setInterval(function() {
@@ -573,7 +581,10 @@ appPanel
     }
 
     function stopAnimation() {
-        clearInterval(animationInterval);
+        if (animationInterval !== undefined) {
+            clearInterval(animationInterval);
+            animationInterval = undefined;
+        }
     }
 
 }());