From 6d5c6b2de75ac8c2d599e2c4ce7f1941f6d1f48f Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Mon, 5 Oct 2015 10:53:41 -0700
Subject: [PATCH] Optimize `_.intersection` and `_.intersectionBy` for empty
 arrays.

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

diff --git a/lodash.js b/lodash.js
index fd1accf57..aed6fb3b4 100644
--- a/lodash.js
+++ b/lodash.js
@@ -5421,7 +5421,7 @@
      */
     var intersection = restParam(function(arrays) {
       var mapped = arrayMap(arrays, toArrayLikeObject);
-      return mapped[0] === arrays[0]
+      return (mapped.length && mapped[0] === arrays[0])
         ? baseIntersection(mapped)
         : [];
     });
@@ -5448,7 +5448,7 @@
      */
     var intersectionBy = restParam(function(arrays) {
       var mapped = arrayMap(arrays, toArrayLikeObject);
-      return mapped[0] === arrays[0]
+      return (mapped.length && mapped[0] === arrays[0])
         ? baseIntersectionBy(mapped, getIteratee(last(arrays)))
         : [];
     });