optmize internal _each, _map, _keys, _forEachOf functions

1 files changed, 18 insertions, 23 deletions

diff --git a/lib/async.js b/lib/async.js
index 81916fd..a1650a7 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -50,26 +50,26 @@
     };
 
     var _each = function (arr, iterator) {
-        for (var i = 0; i < arr.length; i += 1) {
-            iterator(arr[i], i, arr);
-        }
+      var index = -1,
+          length = arr.length;
+
+      while (++index < length) {
+        iterator(arr[index], index, arr);
+      }
     };
 
     var _map = function (arr, iterator) {
-        if (arr.map) {
-            return arr.map(iterator);
-        }
-        var results = [];
-        _each(arr, function (x, i, a) {
-            results.push(iterator(x, i, a));
-        });
-        return results;
+      var index = -1,
+          length = arr.length,
+          result = Array(length);
+
+      while (++index < length) {
+        result[index] = iterator(arr[index], index, arr);
+      }
+      return result;
     };
 
     var _reduce = function (arr, iterator, memo) {
-        if (arr.reduce) {
-            return arr.reduce(iterator, memo);
-        }
         _each(arr, function (x, i, a) {
             memo = iterator(memo, x, i, a);
         });
@@ -77,17 +77,12 @@
     };
 
     var _forEachOf = function (object, iterator) {
-        for (var key in object) {
-            if (object.hasOwnProperty(key)) {
-                iterator(object[key], key);
-            }
-        }
+        _each(_keys(object), function (key) {
+            iterator(object[key], key);
+        });
     };
 
-    var _keys = function (obj) {
-        if (Object.keys) {
-            return Object.keys(obj);
-        }
+    var _keys = Object.keys || function (obj) {
         var keys = [];
         for (var k in obj) {
             if (obj.hasOwnProperty(k)) {