From 1ca26ce6768dc947fb2321a9e8670dbbc25ec47b Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Sat, 22 Sep 2012 15:39:37 -0700
Subject: [PATCH] Ensure methods accepting a `thisArg` argument allow `null`
 values.

Former-commit-id: 368b943687291f0d7ed02304284ac076ef86e02b
---
 build/pre-compile.js |  1 +
 lodash.js            | 31 ++++++++++++------------
 test/test.js         | 56 +++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 72 insertions(+), 16 deletions(-)

diff --git a/build/pre-compile.js b/build/pre-compile.js
index e564f75a7..7b2c582ed 100644
--- a/build/pre-compile.js
+++ b/build/pre-compile.js
@@ -33,6 +33,7 @@
     'stringClass',
     'thisArg',
     'toString',
+    'undefined',
     'value',
 
     // lesser used variables
diff --git a/lodash.js b/lodash.js
index 8595b3e38..b1811a625 100644
--- a/lodash.js
+++ b/lodash.js
@@ -456,8 +456,8 @@
 
   /**
    * Reusable iterator options shared by
-   * `every`, `filter`, `find`, `forEach`, `forIn`, `forOwn`, `groupBy`, `map`,
-   * `reject`, `some`, and `sortBy`.
+   * `countBy`, `every`, `filter`, `find`, `forEach`, `forIn`, `forOwn`, `groupBy`,
+   * `map`, `reject`, `some`, and `sortBy`.
    */
   var baseIteratorOptions = {
     'args': 'collection, callback, thisArg',
@@ -466,7 +466,7 @@
       'if (!callback) {\n' +
       '  callback = identity\n' +
       '}\n' +
-      'else if (thisArg) {\n' +
+      'else if (thisArg !== undefined) {\n' +
       '  callback = bindIterator(callback, thisArg)\n' +
       '}',
     'inLoop': 'if (callback(value, index, collection) === false) return result'
@@ -481,7 +481,7 @@
       '  var valueProp = callback;\n' +
       '  callback = function(value) { return value[valueProp] }\n' +
       '}\n' +
-      'else if (thisArg) {\n' +
+      'else if (thisArg !== undefined) {\n' +
       '  callback = bindIterator(callback, thisArg)\n' +
       '}',
     'inLoop':
@@ -516,7 +516,7 @@
 
   /** Reusable iterator options for `find`, `forEach`, `forIn`, and `forOwn` */
   var forEachIteratorOptions = {
-    'top': 'if (thisArg) callback = bindIterator(callback, thisArg)'
+    'top': 'if (thisArg !== undefined) callback = bindIterator(callback, thisArg)'
   };
 
   /** Reusable iterator options for `forIn` and `forOwn` */
@@ -549,7 +549,7 @@
       'var isFunc = typeof callback == \'function\';\n' +
       'if (!isFunc) {\n' +
       '  var props = concat.apply(ArrayProto, arguments)\n' +
-      '} else if (thisArg) {\n' +
+      '} else if (thisArg !== undefined) {\n' +
       '  callback = bindIterator(callback, thisArg)\n' +
       '}',
     'inLoop':
@@ -792,7 +792,7 @@
         'arrayLikeClasses, ArrayProto, bind, bindIterator, compareAscending, concat, ' +
         'forIn, hasOwnProperty, identity, indexOf, isArguments, isArray, isFunction, ' +
         'isPlainObject, objectClass, objectTypes, nativeKeys, propertyIsEnumerable, ' +
-        'slice, stringClass, toString',
+        'slice, stringClass, toString, undefined',
       'var callee = function(' + args + ') {\n' + iteratorTemplate(data) + '\n};\n' +
       'return callee'
     );
@@ -1862,7 +1862,7 @@
       '    if (prop in object) result[prop] = object[prop]\n' +
       '  }\n' +
       '} else {\n' +
-      '  if (thisArg) callback = bindIterator(callback, thisArg)',
+      '  if (thisArg !== undefined) callback = bindIterator(callback, thisArg)',
     'inLoop':
       'if (callback(value, index, object)) result[index] = value',
     'bottom': '}'
@@ -2184,7 +2184,7 @@
     'init': 'accumulator',
     'top':
       'var noaccum = arguments.length < 3;\n' +
-      'if (thisArg) callback = bindIterator(callback, thisArg)',
+      'if (thisArg !== undefined) callback = bindIterator(callback, thisArg)',
     'beforeLoop': {
       'array': 'if (noaccum) result = iteratee[++index]'
     },
@@ -2763,7 +2763,7 @@
       }
       return result;
     }
-    if (thisArg) {
+    if (thisArg !== undefined) {
       callback = bindIterator(callback, thisArg);
     }
     while (++index < length) {
@@ -2813,7 +2813,7 @@
       }
       return result;
     }
-    if (thisArg) {
+    if (thisArg !== undefined) {
       callback = bindIterator(callback, thisArg);
     }
     while (++index < length) {
@@ -3011,7 +3011,7 @@
         high = array.length;
 
     if (callback) {
-      if (thisArg) {
+      if (thisArg !== undefined) {
         callback = bind(callback, thisArg);
       }
       value = callback(value);
@@ -3105,7 +3105,7 @@
     }
     if (!callback) {
       callback = identity;
-    } else if (thisArg) {
+    } else if (thisArg !== undefined) {
       callback = bindIterator(callback, thisArg);
     }
     while (++index < length) {
@@ -3954,10 +3954,11 @@
    * // => also calls `mage.castSpell(n)` three times
    */
   function times(n, callback, thisArg) {
+    n = +n || 0;
     var index = -1,
-        result = Array(n || 0);
+        result = Array(n);
 
-    if (thisArg) {
+    if (thisArg !== undefined) {
       while (++index < n) {
         result[index] = callback.call(thisArg, index);
       }
diff --git a/test/test.js b/test/test.js
index badf87995..e6c752b07 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1713,7 +1713,61 @@
           }
         });
 
-        ok(pass, methodName + ' allows falsey arguments');
+        ok(pass, '_.' + methodName + ' allows falsey arguments');
+      });
+    });
+
+    test('should handle `null` `thisArg` arguments', function() {
+      var thisArg,
+          array = ['a'],
+          callback = function() { thisArg = this; },
+          useStrict = Function('"use strict";return this')() === undefined;
+
+      var funcs = [
+        'countBy',
+        'every',
+        'filter',
+        'find',
+        'forEach',
+        'forIn',
+        'forOwn',
+        'groupBy',
+        'map',
+        'max',
+        'min',
+        'omit',
+        'pick',
+        'reduce',
+        'reduceRight',
+        'reject',
+        'some',
+        'sortBy',
+        'sortedIndex',
+        'times',
+        'uniq'
+      ];
+
+      _.each(funcs, function(methodName) {
+        var func = _[methodName],
+            message = '_.' + methodName + ' handles `null` `thisArg` arguments';
+
+        thisArg = undefined;
+
+        if (/^reduce/.test(methodName)) {
+          func(array, callback, 0, null);
+        } else if (methodName == 'sortedIndex') {
+          func(array, 'a', callback, null);
+        } else if (methodName == 'times') {
+          func(1, callback, null);
+        } else {
+          func(array, callback, null);
+        }
+
+        if (useStrict) {
+          deepEqual(thisArg, null, message);
+        } else {
+          equal(thisArg, window, message);
+        }
       });
     });
   }());