From a1aa0f8afdc33403604e5415aed649e605e93efd Mon Sep 17 00:00:00 2001
From: Caden Lovelace <caden@herostrat.us>
Date: Sat, 17 Jan 2015 01:14:22 +0000
Subject: Handle multiple zero-offset Scrollspy elements.

When the first two elements in a scrollspy content block have a document
offset of zero (i.e. they're hard against the top of the page),
Scrollspy would switch between them on every scroll event.

This could happen, for example, in a system of nested sections:

```
<section id="animals">
  <section id="dogs">
	Content
  </section>
</section>
```

This ocurred because Scrollspy's check to see if it's at the end of the
array of sections uses `!arr[index]`. This misses the case where
`arr[index]` does exist and is zero.

This commit explicitly checks the array bounds.
---
 js/scrollspy.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'js/scrollspy.js')

diff --git a/js/scrollspy.js b/js/scrollspy.js
index a72bb5350..9b29edf49 100644
--- a/js/scrollspy.js
+++ b/js/scrollspy.js
@@ -96,7 +96,7 @@
     for (i = offsets.length; i--;) {
       activeTarget != targets[i]
         && scrollTop >= offsets[i]
-        && (!offsets[i + 1] || scrollTop <= offsets[i + 1])
+        && (offsets[i + 1] === undefined || scrollTop <= offsets[i + 1])
         && this.activate(targets[i])
     }
   }
-- 
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