From 8c7fcb7781c89cc2d41c415ff5fbb755bbd4000c Mon Sep 17 00:00:00 2001
From: Noah Sloan <iamnoah+github@gmail.com>
Date: Tue, 8 Dec 2009 14:11:28 -0600
Subject: [PATCH] cache is string and toString to improve performance

---
 underscore.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/underscore.js b/underscore.js
index 51398635d..b94cc0f9b 100644
--- a/underscore.js
+++ b/underscore.js
@@ -478,8 +478,9 @@
   // Define the isArray, isDate, isFunction, isNumber, isRegExp, and
   // isString functions based on their toString identifiers.
   _.each(['Array', 'Date', 'Function', 'Number', 'RegExp', 'String'], function(type) {
+	var toString = Object.prototype.toString, typeString = '[object ' + type + ']';
     _['is' + type] = function(obj) {
-      return Object.prototype.toString.call(obj) == '[object ' + type + ']';
+      return toString.call(obj) == typeString;
     };
   });