Optimize _.invert, _.pairs, and _.values.

Former-commit-id: d2725dc8c75254784d450f2a7e997e079b8c3183

build.js

@@ -97,7 +97,7 @@
     'indexOf': ['sortedIndex'],
     'initial': [],
     'intersection': ['indexOf'],
-    'invert': ['forOwn'],
+    'invert': ['keys'],
     'invoke': ['forEach'],
     'isArguments': [],
     'isArray': [],
@@ -129,7 +129,7 @@
     'object': [],
     'omit': ['forIn', 'indexOf'],
     'once': [],
-    'pairs': ['forOwn'],
+    'pairs': ['keys'],
     'partial': ['isFunction', 'isObject'],
     'pick': ['forIn'],
     'pluck': ['map'],
@@ -155,7 +155,7 @@
     'uniq': ['identity', 'indexOf'],
     'uniqueId': [],
     'value': ['mixin'],
-    'values': ['forOwn'],
+    'values': ['keys'],
     'where': ['filter', 'keys'],
     'without': ['indexOf'],
     'wrap': [],

lodash.js

@@ -892,6 +892,26 @@
    */
   var forOwn = createIterator(eachIteratorOptions, forOwnIteratorOptions);
 
+  /**
+   * Creates an array composed of the own enumerable property names of `object`.
+   *
+   * @static
+   * @memberOf _
+   * @category Objects
+   * @param {Object} object The object to inspect.
+   * @returns {Array} Returns a new array of property names.
+   * @example
+   *
+   * _.keys({ 'one': 1, 'two': 2, 'three': 3 });
+   * // => ['one', 'two', 'three'] (order is not guaranteed)
+   */
+  var keys = !nativeKeys ? shimKeys : function(object) {
+    // avoid iterating over the `prototype` property
+    return typeof object == 'function' && propertyIsEnumerable.call(object, 'prototype')
+      ? shimKeys(object)
+      : (isObject(object) ? nativeKeys(object) : []);
+  };
+
   /**
    * A fallback implementation of `isPlainObject` that checks if a given `value`
    * is an object created by the `Object` constructor, assuming objects created
@@ -1179,10 +1199,15 @@
    * // => { 'Moe': 'first', 'Larry': 'second', 'Curly': 'third' } (order is not guaranteed)
    */
   function invert(object) {
-    var result = {};
-    forOwn(object, function(value, key) {
-      result[value] = key;
-    });
+    var index = -1,
+        props = keys(object),
+        length = props.length,
+        result = {};
+
+    while (++index < length) {
+      var key = props[index];
+      result[object[key]] = key;
+    }
     return result;
   }
 
@@ -1684,26 +1709,6 @@
     return typeof value == 'undefined';
   }
 
-  /**
-   * Creates an array composed of the own enumerable property names of `object`.
-   *
-   * @static
-   * @memberOf _
-   * @category Objects
-   * @param {Object} object The object to inspect.
-   * @returns {Array} Returns a new array of property names.
-   * @example
-   *
-   * _.keys({ 'one': 1, 'two': 2, 'three': 3 });
-   * // => ['one', 'two', 'three'] (order is not guaranteed)
-   */
-  var keys = !nativeKeys ? shimKeys : function(object) {
-    // avoid iterating over the `prototype` property
-    return typeof object == 'function' && propertyIsEnumerable.call(object, 'prototype')
-      ? shimKeys(object)
-      : (isObject(object) ? nativeKeys(object) : []);
-  };
-
   /**
    * Merges enumerable properties of the source object(s) into the `destination`
    * object. Subsequent sources will overwrite propery assignments of previous
@@ -1844,10 +1849,15 @@
    * // => [['moe', 30], ['larry', 40], ['curly', 50]] (order is not guaranteed)
    */
   function pairs(object) {
-    var result = [];
-    forOwn(object, function(value, key) {
-      result.push([key, value]);
-    });
+    var index = -1,
+        props = keys(object),
+        length = props.length,
+        result = Array(length);
+
+    while (++index < length) {
+      var key = props[index];
+      result[index] = [key, object[key]];
+    }
     return result;
   }
 
@@ -1914,10 +1924,14 @@
    * // => [1, 2, 3]
    */
   function values(object) {
-    var result = [];
-    forOwn(object, function(value) {
-      result.push(value);
-    });
+    var index = -1,
+        props = keys(object),
+        length = props.length,
+        result = Array(length);
+
+    while (++index < length) {
+      result[index] = object[props[index]];
+    }
     return result;
   }