84 lines
3.4 KiB
Markdown
84 lines
3.4 KiB
Markdown
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---
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id: 5a24c314108439a4d4036172
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title: Render State in the User Interface Another Way
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challengeType: 6
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isRequired: false
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videoUrl: ''
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localeTitle: 用户界面中的渲染状态另一种方式
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---
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## Description
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<section id="description">还有另一种访问组件中<code>state</code>方法。在<code>render()</code>方法中，在<code>return</code>语句之前，您可以直接编写JavaScript。例如，您可以声明函数，从<code>state</code>或<code>props</code>访问数据，对此数据执行计算，等等。然后，您可以将任何数据分配给您可以在<code>return</code>语句中访问的变量。 </section>
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## Instructions
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<section id="instructions">在<code>MyComponent</code> render方法中，定义一个名为<code>name</code>的<code>const</code> ，并将其设置为等于组件<code>state</code>的name值。因为您可以直接在代码的这一部分编写JavaScript，所以您不必将此引用括在花括号中。接下来，在return语句中，使用变量<code>name</code>在<code>h1</code>标记中呈现此值。请记住，您需要在return语句中使用JSX语法（JavaScript的大括号）。 </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: <code>MyComponent</code>应该有一个键<code>name</code> ，其<code>freeCodeCamp</code>值存储在其状态中。
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testString: 'assert(Enzyme.mount(React.createElement(MyComponent)).state("name") === "freeCodeCamp", "<code>MyComponent</code> should have a key <code>name</code> with value <code>freeCodeCamp</code> stored in its state.");'
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- text: <code>MyComponent</code>应该渲染一个包含在单个<code>div</code>的<code>h1</code>标头。
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testString: 'assert(/<div><h1>.*<\/h1><\/div>/.test(Enzyme.mount(React.createElement(MyComponent)).html()), "<code>MyComponent</code> should render an <code>h1</code> header enclosed in a single <code>div</code>.");'
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- text: '渲染的<code>h1</code>标记应包含对<code>{name}</code>的引用。'
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testString: 'getUserInput => assert(/<h1>\n*\s*\{\s*name\s*\}\s*\n*<\/h1>/.test(getUserInput("index")), "The rendered <code>h1</code> tag should include a reference to <code>{name}</code>.");'
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- text: 渲染的<code>h1</code>标头应包含从组件状态呈现的文本。
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testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyComponent)); const first = () => { mockedComponent.setState({ name: "TestName" }); return waitForIt(() => mockedComponent.html()) }; const firstValue = await first(); assert(firstValue === "<div><h1>TestName</h1></div>", "The rendered <code>h1</code> header should contain text rendered from the component's state."); };'
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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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class MyComponent extends React.Component {
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constructor(props) {
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super(props);
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this.state = {
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name: 'freeCodeCamp'
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}
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}
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render() {
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// change code below this line
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// change code above this line
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return (
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<div>
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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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</div>
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### After Test
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<div id='jsx-teardown'>
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```js
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console.info('after the test');
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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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// solution required
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```
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</section>
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