freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/es6/use-class-syntax-to-define-a-constructor-function.md

---
id: 587d7b8b367417b2b2512b53
title: Use class Syntax to Define a Constructor Function
challengeType: 1
forumTopicId: 301212
dashedName: use-class-syntax-to-define-a-constructor-function
---

# --description--

ES6 provides a new syntax to create objects, using the <dfn>class</dfn> keyword.

It should be noted that the `class` syntax is just syntax, and not a full-fledged class-based implementation of an object-oriented paradigm, unlike in languages such as Java, Python, Ruby, etc.

In ES5, we usually define a constructor function and use the `new` keyword to instantiate an object.

```js
var SpaceShuttle = function(targetPlanet){
  this.targetPlanet = targetPlanet;
}
var zeus = new SpaceShuttle('Jupiter');
```

The `class` syntax simply replaces the constructor function creation:

```js
class SpaceShuttle {
  constructor(targetPlanet) {
    this.targetPlanet = targetPlanet;
  }
}
const zeus = new SpaceShuttle('Jupiter');
```

It should be noted that the `class` keyword declares a new function, to which a constructor is added. This constructor is invoked when `new` is called to create a new object.  
**Notes:**

-   UpperCamelCase should be used by convention for ES6 class names, as in `SpaceShuttle` used above.
-   The constructor method is a special method for creating and initializing an object created with a class. You will learn more about it in the Object Oriented Programming section of the JavaScript Algorithms And Data Structures Certification.

# --instructions--

Use the `class` keyword and write a constructor to create the `Vegetable` class.

The `Vegetable` class allows you to create a vegetable object with a property `name` that gets passed to the constructor.

# --hints--

`Vegetable` should be a `class` with a defined `constructor` method.

```js
assert(
  typeof Vegetable === 'function' && typeof Vegetable.constructor === 'function'
);
```

`class` keyword should be used.

```js
assert(code.match(/class/g));
```

`Vegetable` should be able to be instantiated.

```js
assert(() => {
  const a = new Vegetable('apple');
  return typeof a === 'object';
});
```

`carrot.name` should return `carrot`.

```js
assert(carrot.name == 'carrot');
```

# --seed--

## --seed-contents--

```js
// Only change code below this line

// Only change code above this line

const carrot = new Vegetable('carrot');
console.log(carrot.name); // Should display 'carrot'
```

# --solutions--

```js
class Vegetable {
  constructor(name) {
    this.name = name;
  }
}
const carrot = new Vegetable('carrot');
```