135 lines
3.3 KiB
Markdown
135 lines
3.3 KiB
Markdown
---
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id: 5a24c314108439a4d4036164
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title: Create a Component with Composition
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challengeType: 6
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forumTopicId: 301383
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dashedName: create-a-component-with-composition
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---
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# --description--
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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`.
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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:
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```jsx
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return (
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<App>
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<Navbar />
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<Dashboard />
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<Footer />
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</App>
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)
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```
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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`.
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# --instructions--
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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.
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**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.
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# --hints--
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The React component should return a single `div` element.
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```js
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assert(
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(function () {
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var shallowRender = Enzyme.shallow(React.createElement(ParentComponent));
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return shallowRender.type() === 'div';
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})()
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);
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```
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The component should return two nested elements.
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```js
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assert(
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(function () {
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var shallowRender = Enzyme.shallow(React.createElement(ParentComponent));
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return shallowRender.children().length === 2;
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})()
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);
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```
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The component should return the ChildComponent as its second child.
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(ParentComponent));
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return (
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mockedComponent.find('ParentComponent').find('ChildComponent').length ===
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1
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);
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})()
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);
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```
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# --seed--
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## --after-user-code--
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```jsx
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ReactDOM.render(<ParentComponent />, document.getElementById('root'))
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```
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## --seed-contents--
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```jsx
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const ChildComponent = () => {
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return (
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<div>
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<p>I am the child</p>
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</div>
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);
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};
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class ParentComponent extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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return (
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<div>
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<h1>I am the parent</h1>
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{ /* Change code below this line */ }
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{ /* Change code above this line */ }
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</div>
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);
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}
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};
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```
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# --solutions--
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```jsx
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const ChildComponent = () => {
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return (
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<div>
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<p>I am the child</p>
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</div>
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);
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};
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class ParentComponent extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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return (
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<div>
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<h1>I am the parent</h1>
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{ /* Change code below this line */ }
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<ChildComponent />
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{ /* Change code above this line */ }
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</div>
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);
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}
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};
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```
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