2018-10-10 22:03:03 +00:00
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---
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id: 5a24c314108439a4d403616a
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2020-12-16 07:37:30 +00:00
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title: 传递一个数组作为 Props
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2018-10-10 22:03:03 +00:00
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challengeType: 6
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2020-09-17 16:13:42 +00:00
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forumTopicId: 301401
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2021-01-13 02:31:00 +00:00
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dashedName: pass-an-array-as-props
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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上一个挑战演示了如何将来自父组件的信息作为`props`传递给子组件。这个挑战着眼于如何将数组作为`props`传递。要将数组传递给 JSX 元素,必须将其视为 JavaScript 并用花括号括起来。
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2020-09-17 16:13:42 +00:00
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```jsx
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<ParentComponent>
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<ChildComponent colors={["green", "blue", "red"]} />
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</ParentComponent>
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```
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2020-12-16 07:37:30 +00:00
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这样,子组件就可以访问数组属性`colors`。访问属性时可以使用`join()`等数组方法。 `const ChildComponent = (props) => <p>{props.colors.join(', ')}</p>` 这将把所有`colors`数组项连接成一个逗号分隔的字符串并生成: `<p>green, blue, red</p>` 稍后,我们将了解在 React 中渲染数组数据的其他常用方法。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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代码编辑器中有`List`和`ToDo`组件。在`ToDo`组件中渲染每个`List`时,传入`tasks`属性并将其分配给待办任务数组,例如`["walk dog", "workout"]`。然后访问`List`组件中的`tasks`数组,在`p`元素中显示其值。使用`join(", ")`把`props.tasks`数组作为逗号分隔列表显示在`p`元素中。今天的列表应该至少有 2 个任务,明天应该至少有 3 个任务。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`ToDo`组件应该返回单个外部`div`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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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(ToDo));
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return mockedComponent.children().first().type() === 'div';
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})()
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);
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```
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`ToDo`组件的第三个子元素应该是`List`组件的一个实例。
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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(ToDo));
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return mockedComponent.children().first().childAt(2).name() === 'List';
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})()
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-12-16 07:37:30 +00:00
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`ToDo`组件的第五个子元素应该是`List`组件的一个实例。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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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(ToDo));
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return mockedComponent.children().first().childAt(4).name() === 'List';
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`List`组件的两个实例都应该具有一个名为`tasks`的属性,并且`tasks`的类型应该是数组。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(ToDo));
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return (
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Array.isArray(mockedComponent.find('List').get(0).props.tasks) &&
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Array.isArray(mockedComponent.find('List').get(1).props.tasks)
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);
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})()
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-12-16 07:37:30 +00:00
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表示今天任务的第一个`List`组件应该有 2 个或更多项。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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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(ToDo));
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return mockedComponent.find('List').get(0).props.tasks.length >= 2;
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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表示明天任务的第二个`List`组件应该有 3 个或更多项。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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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(ToDo));
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return mockedComponent.find('List').get(1).props.tasks.length >= 3;
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})()
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);
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```
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`List`组件应在`p`标签中渲染`tasks`属性的值。
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2020-09-17 16:13:42 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(ToDo));
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2020-09-17 16:13:42 +00:00
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return (
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2020-12-16 07:37:30 +00:00
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mockedComponent.find('p').get(0).props.children ===
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mockedComponent.find('List').get(0).props.tasks.join(', ') &&
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mockedComponent.find('p').get(1).props.children ===
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mockedComponent.find('List').get(1).props.tasks.join(', ')
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2020-09-17 16:13:42 +00:00
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);
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2020-12-16 07:37:30 +00:00
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})()
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-08-13 15:24:35 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --after-user-code--
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```jsx
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ReactDOM.render(<ToDo />, document.getElementById('root'))
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```
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## --seed-contents--
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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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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```jsx
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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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