From 1681d250635d099fe2d7d88e275322eecb0699af Mon Sep 17 00:00:00 2001
From: Andrei <andrei@nytimes.com>
Date: Thu, 5 May 2011 14:43:28 -0400
Subject: [PATCH] in groupBy, also pass index to iterator.

---
 underscore.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/underscore.js b/underscore.js
index cbcd476e4..a0ad75eec 100644
--- a/underscore.js
+++ b/underscore.js
@@ -254,8 +254,8 @@
   // Groups the object's values by a criterion produced by an iterator
   _.groupBy = function(obj, iterator) {
     var result = {};
-    each(obj, function(value) {
-      var key = iterator(value);
+    each(obj, function(value, index) {
+      var key = iterator(value, index);
       (result[key] || (result[key] = [])).push(value)
     });
     return result;