remove references to native array methods

index.html

@@ -359,10 +359,7 @@
       Underscore provides 80-odd functions that support both the usual
       functional suspects: <b>map</b>, <b>filter</b>, <b>invoke</b> &mdash;
       as well as more specialized helpers: function binding, javascript
-      templating, deep equality testing, and so on. It delegates to built-in
-      functions, if present, so modern browsers will use the
-      native implementations of <b>map</b>, <b>reduce</b>,
-      <b>filter</b>, <b>every</b>, <b>some</b> and <b>indexOf</b>.
+      templating, deep equality testing, and so on.
     </p>
 
     <p>
@@ -467,9 +464,9 @@ <h2 id="collections">Collection Functions (Arrays or Objects)</h2>
         <span class="alias">Alias: <b>collect</b></span>
         <br />
         Produces a new array of values by mapping each value in <b>list</b>
-        through a transformation function (<b>iterator</b>). If the native <b>map</b> method
-        exists, it will be used instead. If <b>list</b> is a JavaScript object,
-        <b>iterator</b>'s arguments will be <tt>(value, key, list)</tt>.
+        through a transformation function (<b>iterator</b>). If <b>list</b>
+        is a JavaScript object, <b>iterator</b>'s arguments will be
+        <tt>(value, key, list)</tt>.
       </p>
       <pre>
 _.map([1, 2, 3], function(num){ return num * 3; });
@@ -528,8 +525,7 @@ <h2 id="collections">Collection Functions (Arrays or Objects)</h2>
         <span class="alias">Alias: <b>select</b></span>
         <br />
         Looks through each value in the <b>list</b>, returning an array of all
-        the values that pass a truth test (<b>predicate</b>). Delegates to the
-        native <b>filter</b> method, if it exists.
+        the values that pass a truth test (<b>predicate</b>).
       </p>
       <pre>
 var evens = _.filter([1, 2, 3, 4, 5, 6], function(num){ return num % 2 == 0; });
@@ -581,8 +577,8 @@ <h2 id="collections">Collection Functions (Arrays or Objects)</h2>
         <b class="header">every</b><code>_.every(list, [predicate], [context])</code>
         <span class="alias">Alias: <b>all</b></span>
         <br />
-        Returns <i>true</i> if all of the values in the <b>list</b> pass the <b>predicate</b>
-        truth test. Delegates to the native method <b>every</b>, if present.
+        Returns <i>true</i> if all of the values in the <b>list</b> pass the
+        <b>predicate</b> truth test.
       </p>
       <pre>
 _.every([true, 1, null, 'yes'], _.identity);
@@ -595,8 +591,7 @@ <h2 id="collections">Collection Functions (Arrays or Objects)</h2>
         <br />
         Returns <i>true</i> if any of the values in the <b>list</b> pass the
         <b>predicate</b> truth test. Short-circuits and stops traversing the list
-        if a true element is found. Delegates to the native method <b>some</b>,
-        if present.
+        if a true element is found.
       </p>
       <pre>
 _.some([null, 0, 'yes', false]);
@@ -963,8 +958,7 @@ <h2 id="arrays">Array Functions</h2>
         <b class="header">indexOf</b><code>_.indexOf(array, value, [isSorted])</code>
         <br />
         Returns the index at which <b>value</b> can be found in the <b>array</b>,
-        or <i>-1</i> if value is not present in the <b>array</b>. Uses the native
-        <b>indexOf</b> function unless it's missing. If you're working with a
+        or <i>-1</i> if value is not present in the <b>array</b>. If you're working with a
         large array, and you know that the array is already sorted, pass <tt>true</tt>
         for <b>isSorted</b> to use a faster binary search ... or, pass a number as
         the third argument in order to look for the first matching value in the
@@ -979,8 +973,7 @@ <h2 id="arrays">Array Functions</h2>
         <b class="header">lastIndexOf</b><code>_.lastIndexOf(array, value, [fromIndex])</code>
         <br />
         Returns the index of the last occurrence of <b>value</b> in the <b>array</b>,
-        or <i>-1</i> if value is not present. Uses the native <b>lastIndexOf</b>
-        function if possible. Pass <b>fromIndex</b> to start your search at a
+        or <i>-1</i> if value is not present. Pass <b>fromIndex</b> to start your search at a
         given index.
       </p>
       <pre>

test/arrays.js

@@ -214,6 +214,9 @@
     numbers = [1, 2, 3, 1, 2, 3, 1, 2, 3];
     index = _.indexOf(numbers, 2, 5);
     equal(index, 7, 'supports the fromIndex argument');
+
+    index = _.indexOf([,,,], undefined);
+    equal(index, 0, 'treats sparse arrays as if they were dense');
   });
 
   test('lastIndexOf', function() {

underscore.js

@@ -31,14 +31,6 @@
   // All **ECMAScript 5** native function implementations that we hope to use
   // are declared here.
   var
-    nativeMap          = ArrayProto.map,
-    nativeReduce       = ArrayProto.reduce,
-    nativeReduceRight  = ArrayProto.reduceRight,
-    nativeFilter       = ArrayProto.filter,
-    nativeEvery        = ArrayProto.every,
-    nativeSome         = ArrayProto.some,
-    nativeIndexOf      = ArrayProto.indexOf,
-    nativeLastIndexOf  = ArrayProto.lastIndexOf,
     nativeIsArray      = Array.isArray,
     nativeKeys         = Object.keys,
     nativeBind         = FuncProto.bind;
@@ -88,11 +80,9 @@
   };
 
   // Return the results of applying the iterator to each element.
-  // Delegates to **ECMAScript 5**'s native `map` if available.
   _.map = _.collect = function(obj, iterator, context) {
     var results = [];
     if (obj == null) return results;
-    if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
     _.each(obj, function(value, index, list) {
       results.push(iterator.call(context, value, index, list));
     });
@@ -102,14 +92,10 @@
   var reduceError = 'Reduce of empty array with no initial value';
 
   // **Reduce** builds up a single result from a list of values, aka `inject`,
-  // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
+  // or `foldl`.
   _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
     var initial = arguments.length > 2;
     if (obj == null) obj = [];
-    if (nativeReduce && obj.reduce === nativeReduce) {
-      if (context) iterator = _.bind(iterator, context);
-      return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
-    }
     _.each(obj, function(value, index, list) {
       if (!initial) {
         memo = value;
@@ -123,14 +109,9 @@
   };
 
   // The right-associative version of reduce, also known as `foldr`.
-  // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
   _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
     var initial = arguments.length > 2;
     if (obj == null) obj = [];
-    if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
-      if (context) iterator = _.bind(iterator, context);
-      return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
-    }
     var length = obj.length;
     if (length !== +length) {
       var keys = _.keys(obj);
@@ -162,12 +143,10 @@
   };
 
   // Return all the elements that pass a truth test.
-  // Delegates to **ECMAScript 5**'s native `filter` if available.
   // Aliased as `select`.
   _.filter = _.select = function(obj, predicate, context) {
     var results = [];
     if (obj == null) return results;
-    if (nativeFilter && obj.filter === nativeFilter) return obj.filter(predicate, context);
     _.each(obj, function(value, index, list) {
       if (predicate.call(context, value, index, list)) results.push(value);
     });
@@ -180,27 +159,23 @@
   };
 
   // Determine whether all of the elements match a truth test.
-  // Delegates to **ECMAScript 5**'s native `every` if available.
   // Aliased as `all`.
   _.every = _.all = function(obj, predicate, context) {
     predicate || (predicate = _.identity);
     var result = true;
     if (obj == null) return result;
-    if (nativeEvery && obj.every === nativeEvery) return obj.every(predicate, context);
     _.each(obj, function(value, index, list) {
       if (!(result = result && predicate.call(context, value, index, list))) return breaker;
     });
     return !!result;
   };
 
   // Determine if at least one element in the object matches a truth test.
-  // Delegates to **ECMAScript 5**'s native `some` if available.
   // Aliased as `any`.
   _.some = _.any = function(obj, predicate, context) {
     predicate || (predicate = _.identity);
     var result = false;
     if (obj == null) return result;
-    if (nativeSome && obj.some === nativeSome) return obj.some(predicate, context);
     _.each(obj, function(value, index, list) {
       if (result || (result = predicate.call(context, value, index, list))) return breaker;
     });
@@ -211,7 +186,6 @@
   // Aliased as `include`.
   _.contains = _.include = function(obj, target) {
     if (obj == null) return false;
-    if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
     return _.some(obj, function(value) {
       return value === target;
     });
@@ -559,7 +533,6 @@
   // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
   // we need this function. Return the position of the first occurrence of an
   // item in an array, or -1 if the item is not included in the array.
-  // Delegates to **ECMAScript 5**'s native `indexOf` if available.
   // If the array is large and already in sort order, pass `true`
   // for **isSorted** to use binary search.
   _.indexOf = function(array, item, isSorted) {
@@ -573,19 +546,13 @@
         return array[i] === item ? i : -1;
       }
     }
-    if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
     for (; i < length; i++) if (array[i] === item) return i;
     return -1;
   };
 
-  // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
   _.lastIndexOf = function(array, item, from) {
     if (array == null) return -1;
-    var hasIndex = from != null;
-    if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
-      return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
-    }
-    var i = (hasIndex ? from : array.length);
+    var i = from == null ? array.length : from;
     while (i--) if (array[i] === item) return i;
     return -1;
   };