78 lines
3.7 KiB
Markdown
78 lines
3.7 KiB
Markdown
|
---
|
|||
|
|
id: 5a24c314108439a4d4036170
|
|||
|
|
title: Create a Stateful Component
|
|||
|
|
challengeType: 6
|
|||
|
|
isRequired: false
|
|||
|
|
videoUrl: ''
|
|||
|
|
localeTitle: 创建一个有状态组件
|
|||
|
|
---
|
|||
|
|
|
|||
|
|
## Description
|
|||
|
|
<section id="description"> React最重要的主题之一是<code>state</code> 。 State包含应用程序需要了解的任何数据，这些数据可能会随时间而变化。您希望应用程序响应状态更改并在必要时显示更新的UI。 React为现代Web应用程序的状态管理提供了一个很好的解决方案。您可以通过在<code>constructor</code>声明组件类的<code>state</code>属性来在React组件中创建状态。这与初始化该组件<code>state</code>被创建时。 <code>state</code>属性必须设置为JavaScript <code>object</code> 。声明它看起来像这样： <blockquote> this.state = { <br> //在这里描述你的州<br>您可以在组件的整个生命周期内访问<code>state</code>对象。您可以更新它，在UI中呈现它，并将其作为道具传递给子组件。 <code>state</code>对象可以像您需要的那样复杂或简单。请注意，您必须通过扩展<code>React.Component</code>来创建类组件，以便创建这样的<code>state</code> 。 </blockquote></section>
|
|||
|
|
|
|||
|
|
## Instructions
|
|||
|
|
<section id="instructions">代码编辑器中有一个组件试图从其<code>state</code>呈现<code>name</code>属性。但是，没有定义<code>state</code> 。初始化与组件<code>state</code>的<code>constructor</code> ，并指定你的名字的属性<code>name</code> 。 </section>
|
|||
|
|
|
|||
|
|
## Tests
|
|||
|
|
<section id='tests'>
|
|||
|
|
|
|||
|
|
```yml
|
|||
|
|
tests:
|
|||
|
|
- text: <code>StatefulComponent</code>应该存在并呈现。
|
|||
|
|
testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(StatefulComponent)); return mockedComponent.find("StatefulComponent").length === 1; })(), "<code>StatefulComponent</code> should exist and render.");'
|
|||
|
|
- text: <code>StatefulComponent</code>应该呈现<code>div</code>和<code>h1</code>元素。
|
|||
|
|
testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(StatefulComponent)); return mockedComponent.find("div").length === 1 && mockedComponent.find("h1").length === 1; })(), "<code>StatefulComponent</code> should render a <code>div</code> and an <code>h1</code> element.");'
|
|||
|
|
- text: 应使用设置为字符串的属性<code>name</code>初始化<code>StatefulComponent</code> 。
|
|||
|
|
testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(StatefulComponent)); const initialState = mockedComponent.state(); return ( typeof initialState === "object" && typeof initialState.name === "string"); })(), "The state of <code>StatefulComponent</code> should be initialized with a property <code>name</code> set to a string.");'
|
|||
|
|
- text: <code>StatefulComponent</code>的属性<code>name</code>应在<code>h1</code>元素中呈现。
|
|||
|
|
testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(StatefulComponent)); const initialState = mockedComponent.state(); return mockedComponent.find("h1").text() === initialState.name; })(), "The property <code>name</code> in the state of <code>StatefulComponent</code> should render in the <code>h1</code> element.");'
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</section>
|
|||
|
|
|
|||
|
|
## Challenge Seed
|
|||
|
|
<section id='challengeSeed'>
|
|||
|
|
|
|||
|
|
<div id='jsx-seed'>
|
|||
|
|
|
|||
|
|
```jsx
|
|||
|
|
class StatefulComponent extends React.Component {
|
|||
|
|
constructor(props) {
|
|||
|
|
super(props);
|
|||
|
|
// initialize state here
|
|||
|
|
|
|||
|
|
}
|
|||
|
|
render() {
|
|||
|
|
return (
|
|||
|
|
<div>
|
|||
|
|
<h1>{this.state.name}</h1>
|
|||
|
|
</div>
|
|||
|
|
);
|
|||
|
|
}
|
|||
|
|
};
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
### After Test
|
|||
|
|
<div id='jsx-teardown'>
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
console.info('after the test');
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
</section>
|
|||
|
|
|
|||
|
|
## Solution
|
|||
|
|
<section id='solution'>
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
// solution required
|
|||
|
|
```
|
|||
|
|
</section>
|