Add baseDifference to optimize _.omit & _.without.

lodash.js

@@ -1249,6 +1249,43 @@
       return bound;
     }
 
+    /**
+     * The base implementation of `_.difference` that accepts a single array
+     * of values to exclude.
+     *
+     * @private
+     * @param {Array} array The array to process.
+     * @param {Array} [values] The array of values to exclude.
+     * @returns {Array} Returns a new array of filtered values.
+     */
+    function baseDifference(array, values) {
+      var index = -1,
+          indexOf = getIndexOf(),
+          length = array ? array.length : 0,
+          isLarge = length >= largeArraySize && indexOf === baseIndexOf,
+          result = [];
+
+      if (isLarge) {
+        var cache = createCache(values);
+        if (cache) {
+          indexOf = cacheIndexOf;
+          values = cache;
+        } else {
+          isLarge = false;
+        }
+      }
+      while (++index < length) {
+        var value = array[index];
+        if (indexOf(values, value) < 0) {
+          result.push(value);
+        }
+      }
+      if (isLarge) {
+        releaseObject(values);
+      }
+      return result;
+    }
+
     /**
      * The base implementation of `_.flatten` without support for callback
      * shorthands or `thisArg` binding.
@@ -2995,7 +3032,7 @@
         forIn(object, function(value, key) {
           props.push(key);
         });
-        props = difference(props, baseFlatten(arguments, true, false, 1));
+        props = baseDifference(props, baseFlatten(arguments, true, false, 1));
 
         var index = -1,
             length = props.length;
@@ -4374,7 +4411,7 @@
      * @memberOf _
      * @category Arrays
      * @param {Array} array The array to process.
-     * @param {...Array} [array] The arrays of values to exclude.
+     * @param {...Array} [values] The arrays of values to exclude.
      * @returns {Array} Returns a new array of filtered values.
      * @example
      *
@@ -4382,33 +4419,7 @@
      * // => [1, 3, 4]
      */
     function difference(array) {
-      var index = -1,
-          indexOf = getIndexOf(),
-          length = array ? array.length : 0,
-          seen = baseFlatten(arguments, true, true, 1),
-          result = [];
-
-      var isLarge = length >= largeArraySize && indexOf === baseIndexOf;
-
-      if (isLarge) {
-        var cache = createCache(seen);
-        if (cache) {
-          indexOf = cacheIndexOf;
-          seen = cache;
-        } else {
-          isLarge = false;
-        }
-      }
-      while (++index < length) {
-        var value = array[index];
-        if (indexOf(seen, value) < 0) {
-          result.push(value);
-        }
-      }
-      if (isLarge) {
-        releaseObject(seen);
-      }
-      return result;
+      return baseDifference(array, baseFlatten(arguments, true, true, 1));
     }
 
     /**
@@ -5272,7 +5283,7 @@
      * // => [2, 3, 4]
      */
     function without(array) {
-      return difference(array, slice(arguments, 1));
+      return baseDifference(array, slice(arguments, 1));
     }
 
     /**