From 3c5686f7842a2f52e1692348a848124d3578b993 Mon Sep 17 00:00:00 2001
From: Jeremy Ashkenas <jashkenas@gmail.com>
Date: Fri, 16 Dec 2011 12:41:20 -0500
Subject: [PATCH] Fixes #403

---
 test/collections.js | 7 +++++--
 test/functions.js   | 7 +++----
 underscore.js       | 1 +
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/test/collections.js b/test/collections.js
index 499432ac1..e66dac48b 100644
--- a/test/collections.js
+++ b/test/collections.js
@@ -49,6 +49,9 @@ $(document).ready(function() {
 
     var ifnull = _.map(null, function(){});
     ok(_.isArray(ifnull) && ifnull.length === 0, 'handles a null properly');
+
+    var length = _.map(Array(2), function(v) { return v; }).length;
+    equals(length, 2, "can preserve a sparse array's length");
   });
 
   test('collections: reduce', function() {
@@ -83,7 +86,7 @@ $(document).ready(function() {
     var sparseArray = [];
     sparseArray[0] = 20;
     sparseArray[2] = -5;
-    equals(_.reduce(sparseArray, function(a, b){ return a - b }), 25, 'initially-sparse arrays with no memo');
+    equals(_.reduce(sparseArray, function(a, b){ return a - b; }), 25, 'initially-sparse arrays with no memo');
   });
 
   test('collections: reduceRight', function() {
@@ -112,7 +115,7 @@ $(document).ready(function() {
     var sparseArray = [];
     sparseArray[0] = 20;
     sparseArray[2] = -5;
-    equals(_.reduceRight(sparseArray, function(a, b){ return a - b }), -25, 'initially-sparse arrays with no memo');
+    equals(_.reduceRight(sparseArray, function(a, b){ return a - b; }), -25, 'initially-sparse arrays with no memo');
   });
 
   test('collections: detect', function() {
diff --git a/test/functions.js b/test/functions.js
index f084b015e..fdaddcc96 100644
--- a/test/functions.js
+++ b/test/functions.js
@@ -112,10 +112,9 @@ $(document).ready(function() {
     throttledUpdate(1); throttledUpdate(2); throttledUpdate(3);
     setTimeout(function(){ throttledUpdate(4); }, 120);
     setTimeout(function(){ throttledUpdate(5); }, 140);
-    setTimeout(function(){ throttledUpdate(6); }, 260);
-    setTimeout(function(){ throttledUpdate(7); }, 270);
-    _.delay(function(){ ok(value == 1, "updated to latest value"); }, 40);
-    _.delay(function(){ ok(value == 7, "updated to latest value"); start(); }, 400);
+    setTimeout(function(){ throttledUpdate(6); }, 250);
+    _.delay(function(){ equals(value, 1, "updated to latest value"); }, 40);
+    _.delay(function(){ equals(value, 6, "updated to latest value"); start(); }, 400);
   });
 
   asyncTest("functions: throttle once", 1, function() {
diff --git a/underscore.js b/underscore.js
index b6b28137d..748ea920c 100644
--- a/underscore.js
+++ b/underscore.js
@@ -102,6 +102,7 @@
     each(obj, function(value, index, list) {
       results[results.length] = iterator.call(context, value, index, list);
     });
+    if (obj.length === +obj.length) results.length = obj.length;
     return results;
   };