Ensure bound result of _.bind(func, …) is an instance of bound and func.

Former-commit-id: d8176ad5eb45a3d675617676fc1eee4d9cbd6ebc

lodash.js

@@ -609,19 +609,19 @@
           : partialArgs;
       }
       if (this instanceof bound) {
-        // get `func` instance if `bound` is invoked in a `new` expression
-        noop.prototype = func.prototype;
-        thisBinding = new noop;
-
         // mimic the constructor's `return` behavior
         // http://es5.github.com/#x13.2.2
-        var result = func.apply(thisBinding, args);
-        return isObject(result)
-          ? result
-          : thisBinding
+        var result = func.apply(this, args);
+        return isObject(result) ? result : this;
       }
       return func.apply(thisBinding, args);
     }
+    if (func && func.prototype) {
+      // ensure `new bound` is an instance of `bound` and `func`
+      noop.prototype = func.prototype;
+      bound.prototype = new noop
+      noop.prototype = null;
+    }
     return bound;
   }
 

test/test.js

@@ -209,6 +209,14 @@
       bound(['b'], 'c');
       deepEqual(args, ['a', ['b'], 'c']);
     });
+
+    test('ensure `new bound` is an instance of `bound` and `func`', function() {
+      var func = function() {},
+          bound = _.bind(func, {}),
+          instance = new bound;
+
+      ok(instance instanceof bound && instance instanceof func);
+    });
   }());
 
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