Add support for maps and sets to _.isEmpty. [closes #2159]

lodash.js

@@ -10361,11 +10361,15 @@
     }
 
     /**
-     * Checks if `value` is an empty object or collection. A value is considered
+     * Checks if `value` is an empty object, collection, map, or set.
-     * empty if it's an `arguments` object, array, buffer, string, or jQuery-like
+     *
-     * collection with a length of `0` or has no own enumerable string keyed
+     * Objects are considered empty if they have no own enumerable string keyed
      * properties.
      *
+     * Array-like values such as `arguments` objects, arrays, buffers, strings, or
+     * jQuery-like collections are considered empty if they have a `length` of `0`.
+     * Similarly, maps and sets are considered empty if they have a `size` of `0`.
+     *
      * @static
      * @memberOf _
      * @since 0.1.0
@@ -10400,6 +10404,12 @@
           return false;
         }
       }
+      if (isObjectLike(value)) {
+        var tag = getTag(value);
+        if (tag == mapTag || tag == setTag) {
+          return !value.size;
+        }
+      }
       return true;
     }
 

test/test.js

@@ -8744,6 +8744,38 @@
       assert.strictEqual(_.isEmpty(new Foo([])), true);
     });
 
+    QUnit.test('should work with maps', function(assert) {
+      assert.expect(4);
+
+      if (Map) {
+        lodashStable.each([new Map, realm.map], function(map) {
+          assert.strictEqual(_.isEmpty(map), true);
+          map.set('a', 1);
+          assert.strictEqual(_.isEmpty(map), false);
+          map.clear();
+        });
+      }
+      else {
+        skipAssert(assert, 4);
+      }
+    });
+
+    QUnit.test('should work with sets', function(assert) {
+      assert.expect(4);
+
+      if (Set) {
+        lodashStable.each([new Set, realm.set], function(set) {
+          assert.strictEqual(_.isEmpty(set), true);
+          set.add(1);
+          assert.strictEqual(_.isEmpty(set), false);
+          set.clear();
+        });
+      }
+      else {
+        skipAssert(assert, 4);
+      }
+    });
+
     QUnit.test('should not treat objects with negative lengths as array-like', function(assert) {
       assert.expect(1);