122 lines
6.0 KiB
Markdown
122 lines
6.0 KiB
Markdown
---
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id: 5a24c314108439a4d403616a
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title: Pass an Array as Props
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challengeType: 6
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isRequired: false
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---
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## Description
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<section id='description'>
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The last challenge demonstrated how to pass information from a parent component to a child component as <code>props</code> or properties. This challenge looks at how arrays can be passed as <code>props</code>. To pass an array to a JSX element, it must be treated as JavaScript and wrapped in curly braces.
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<blockquote><ParentComponent><br> <ChildComponent colors={["green", "blue", "red"]} /><br></ParentComponent></blockquote>
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The child component then has access to the array property <code>colors</code>. Array methods such as <code>join()</code> can be used when accessing the property.
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<code>const ChildComponent = (props) => <p>{props.colors.join(', ')}</p></code>
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This will join all <code>colors</code> array items into a comma separated string and produce:
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<code> <p>green, blue, red</p></code>
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Later, we will learn about other common methods to render arrays of data in React.
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</section>
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## Instructions
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<section id='instructions'>
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There are <code>List</code> and <code>ToDo</code> components in the code editor. When rendering each <code>List</code> from the <code>ToDo</code> component, pass in a <code>tasks</code> property assigned to an array of to-do tasks, for example <code>["walk dog", "workout"]</code>. Then access this <code>tasks</code> array in the <code>List</code> component, showing its value within the <code>p</code> element. Use <code>join(", ")</code> to display the <code>props.tasks</code>array in the <code>p</code> element as a comma separated list. Today's list should have at least 2 tasks and tomorrow's should have at least 3 tasks.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: The <code>ToDo</code> component should return a single outer <code>div</code>.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.children().first().type() === 'div'; })(), 'The <code>ToDo</code> component should return a single outer <code>div</code>.');
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- text: The third child of the <code>ToDo</code> component should be an instance of the <code>List</code> component.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.children().first().childAt(2).name() === 'List'; })(), 'The third child of the <code>ToDo</code> component should be an instance of the <code>List</code> component.');
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- text: The fifth child of the <code>ToDo</code> component should be an instance of the <code>List</code> component.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.children().first().childAt(4).name() === 'List'; })(), 'The fifth child of the <code>ToDo</code> component should be an instance of the <code>List</code> component.');
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- text: Both instances of the <code>List</code> component should have a property called <code>tasks</code> and <code>tasks</code> should be of type array.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return Array.isArray(mockedComponent.find('List').get(0).props.tasks) && Array.isArray(mockedComponent.find('List').get(1).props.tasks); })(), 'Both instances of the <code>List</code> component should have a property called <code>tasks</code> and <code>tasks</code> should be of type array.');
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- text: The first <code>List</code> component representing the tasks for today should have 2 or more items.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.find('List').get(0).props.tasks.length >= 2; })(), 'The first <code>List</code> component representing the tasks for today should have 2 or more items.');
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- text: The second <code>List</code> component representing the tasks for tomorrow should have 3 or more items.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.find('List').get(1).props.tasks.length >= 3; })(), 'The second <code>List</code> component representing the tasks for tomorrow should have 3 or more items.');
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- text: The <code>List</code> component should render the value from the <code>tasks</code> prop in the <code>p</code> tag.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(ToDo)); return mockedComponent.find('p').get(0).props.children === mockedComponent.find('List').get(0).props.tasks.join(', ') && mockedComponent.find('p').get(1).props.children === mockedComponent.find('List').get(1).props.tasks.join(', '); })(), 'The <code>List</code> component should render the value from the <code>tasks</code> prop in the <code>p</code> tag.');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='jsx-seed'>
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```jsx
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const List= (props) => {
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{ /* change code below this line */ }
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return <p>{}</p>
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{ /* change code above this line */ }
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};
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class ToDo 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>To Do Lists</h1>
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<h2>Today</h2>
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{ /* change code below this line */ }
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<List/>
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<h2>Tomorrow</h2>
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<List/>
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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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</div>
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### After Test
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<div id='jsx-teardown'>
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```js
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ReactDOM.render(<ToDo />, document.getElementById('root'))
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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const List= (props) => {
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return <p>{props.tasks.join(', ')}</p>
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};
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class ToDo 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>To Do Lists</h1>
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<h2>Today</h2>
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<List tasks={['study', 'exercise']} />
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<h2>Tomorrow</h2>
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<List tasks={['call Sam', 'grocery shopping', 'order tickets']} />
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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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</section>
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