Add Array#intersect for set intersection. Returns a new array containing all items common to the array and the argument, with duplicates removed (clone of the Ruby & method).

CHANGELOG

@@ -1,5 +1,9 @@
 *SVN*
 
+* Add Array#intersect for set intersection. Returns a new array containing all items common to the array and the argument, with duplicates removed (clone of the Ruby & method).   [Thomas Fuchs]
+  Example:
+    [1,1,3,5].intersect([1,2,3]) -> [1,3]
+
 * Rename Element#getElementsBySelector to Element#select and add alias for Element#getElementsBySelector.  [Thomas Fuchs]
 
 * Add Element#adjacent as a shortcut to selecting all adjacent nodes (and their children) that match a CSS selector.  [Thomas Fuchs]

src/array.js

@@ -85,6 +85,12 @@ Object.extend(Array.prototype, {
     });
   },
   
+  intersect: function(array) { 
+    return this.uniq().findAll(function(item) { 
+      return array.include(item);
+    }); 
+  },
+  
   clone: function() {
     return [].concat(this);
   },

test/unit/array.html

@@ -147,6 +147,18 @@
       assertEqual('[\'a\', 1]',['a',1].inspect());
     }},
     
+    testIntersect: function(){ with(this) {
+      assertEnumEqual([1,3], [1,1,3,5].intersect([1,2,3]));
+      assertEnumEqual([1], [1,1].intersect([1,1]));
+      assertEnumEqual([], [1,1,3,5].intersect([4]));
+      assertEnumEqual([], [1].intersect(['1']));
+      
+      assertEnumEqual(
+        ['B','C','D'], 
+        $R('A','Z').toArray().intersect($R('B','D').toArray())
+      );
+    }},
+    
     testToJSON: function(){ with(this) {
       assertEqual('[]', [].toJSON());
       assertEqual('[\"a\"]', ['a'].toJSON());