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id	title	challengeType	isRequired
5a24c314108439a4d4036164	Create a Component with Composition	6	false

Description

Now we will look at how we can compose multiple React components together. Imagine you are building an App and have created three components, a Navbar, Dashboard, and Footer. To compose these components together, you could create an App parent component which renders each of these three components as children. To render a component as a child in a React component, you include the component name written as a custom HTML tag in the JSX. For example, in the render method you could write:

return (
<App>
  <Navbar />
  <Dashboard />
  <Footer />
</App>
)

When React encounters a custom HTML tag that references another component (a component name wrapped in < /> like in this example), it renders the markup for that component in the location of the tag. This should illustrate the parent/child relationship between the App component and the Navbar, Dashboard, and Footer.

Instructions

In the code editor, there is a simple functional component called ChildComponent and a class component called ParentComponent. Compose the two together by rendering the ChildComponent within the ParentComponent. Make sure to close the ChildComponent tag with a forward slash. Note: ChildComponent is defined with an ES6 arrow function because this is a very common practice when using React. However, know that this is just a function. If you aren't familiar with the arrow function syntax, please refer to the JavaScript section.

Tests

tests:
  - text: The React component should return a single <code>div</code> element.
    testString: assert((function() { var shallowRender = Enzyme.shallow(React.createElement(ParentComponent)); return shallowRender.type() === 'div'; })(), 'The React component should return a single <code>div</code> element.');
  - text: The component should return two nested elements.
    testString: assert((function() { var shallowRender = Enzyme.shallow(React.createElement(ParentComponent)); return shallowRender.children().length === 2; })(), 'The component should return two nested elements.');
  - text: The component should return the ChildComponent as its second child.
    testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ParentComponent)); return mockedComponent.find('ParentComponent').find('ChildComponent').length === 1; })(), 'The component should return the ChildComponent as its second child.');

Challenge Seed

const ChildComponent = () => {
  return (
    <div>
      <p>I am the child</p>
    </div>
  );
};

class ParentComponent extends React.Component {
  constructor(props) {
    super(props);
  }
  render() {
    return (
      <div>
        <h1>I am the parent</h1>
        { /* change code below this line */ }


        { /* change code above this line */ }
      </div>
    );
  }
};

After Test

ReactDOM.render(<ParentComponent />, document.getElementById('root'))

Solution

const ChildComponent = () => {
  return (
    <div>
      <p>I am the child</p>
    </div>
  );
};

class ParentComponent extends React.Component {
  constructor(props) {
    super(props);
  }
  render() {
    return (
      <div>
        <h1>I am the parent</h1>
        { /* change code below this line */ }
        <ChildComponent />
        { /* change code above this line */ }
      </div>
    );
  }
};

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