From dc9b320c4addbb91277ec2074cdcbe35af6ef73e Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Thu, 25 Sep 2014 09:42:27 -0700
Subject: [PATCH] Ensure `_.indexOf` and `_.lastIndexOf` match `NaN` when
 performing a binary search.

---
 lodash.js    | 9 ++++++---
 test/test.js | 3 ++-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/lodash.js b/lodash.js
index b1ba43f2d..6871ef29b 100644
--- a/lodash.js
+++ b/lodash.js
@@ -3683,8 +3683,10 @@
       if (typeof fromIndex == 'number') {
         fromIndex = fromIndex < 0 ? nativeMax(length + fromIndex, 0) : (fromIndex || 0);
       } else if (fromIndex) {
-        var index = sortedIndex(array, value);
-        return array[index] === value ? index : -1;
+        var index = sortedIndex(array, value),
+            other = array[index];
+
+        return (value === value ? value === other : other !== other) ? index : -1;
       }
       return baseIndexOf(array, value, fromIndex);
     }
@@ -3821,7 +3823,8 @@
         index = (fromIndex < 0 ? nativeMax(length + fromIndex, 0) : nativeMin(fromIndex || 0, length - 1)) + 1;
       } else if (fromIndex) {
         index = sortedLastIndex(array, value) - 1;
-        return array[index] === value ? index : -1;
+        var other = array[index];
+        return (value === value ? value === other : other !== other) ? index : -1;
       }
       if (value !== value) {
         return indexOfNaN(array, index, true);
diff --git a/test/test.js b/test/test.js
index 383abeb94..f1cc2c464 100644
--- a/test/test.js
+++ b/test/test.js
@@ -7066,8 +7066,9 @@
       strictEqual(func(empty, undefined, true), -1);
     });
 
-    test('`_.' + methodName + '` should match `NaN`', 1, function() {
+    test('`_.' + methodName + '` should match `NaN`', 2, function() {
       strictEqual(func([1, NaN, 3], NaN), 1);
+      strictEqual(func([1, 3, NaN], NaN, true), 2);
     });
   });