freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/object-oriented-programming/reset-an-inherited-constructor-property.md

---
id: 587d7db1367417b2b2512b86
title: Reset an Inherited Constructor Property
challengeType: 1
forumTopicId: 301324
dashedName: reset-an-inherited-constructor-property
---

# --description--

When an object inherits its `prototype` from another object, it also inherits the supertype's constructor property.

Here's an example:

```js
function Bird() { }
Bird.prototype = Object.create(Animal.prototype);
let duck = new Bird();
duck.constructor // function Animal(){...}
```

But `duck` and all instances of `Bird` should show that they were constructed by `Bird` and not `Animal`. To do so, you can manually set `Bird's` constructor property to the `Bird` object:

```js
Bird.prototype.constructor = Bird;
duck.constructor // function Bird(){...}
```

# --instructions--

Fix the code so `duck.constructor` and `beagle.constructor` return their respective constructors.

# --hints--

`Bird.prototype` should be an instance of `Animal`.

```js
assert(Animal.prototype.isPrototypeOf(Bird.prototype));
```

`duck.constructor` should return `Bird`.

```js
assert(duck.constructor === Bird);
```

`Dog.prototype` should be an instance of `Animal`.

```js
assert(Animal.prototype.isPrototypeOf(Dog.prototype));
```

`beagle.constructor` should return `Dog`.

```js
assert(beagle.constructor === Dog);
```

# --seed--

## --seed-contents--

```js
function Animal() { }
function Bird() { }
function Dog() { }

Bird.prototype = Object.create(Animal.prototype);
Dog.prototype = Object.create(Animal.prototype);

// Only change code below this line



let duck = new Bird();
let beagle = new Dog();
```

# --solutions--

```js
function Animal() { }
function Bird() { }
function Dog() { }
Bird.prototype = Object.create(Animal.prototype);
Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;
Bird.prototype.constructor = Bird;
let duck = new Bird();
let beagle = new Dog();
```