freeCodeCamp/create-a-controlled-form.chinese.md at ff8db8ce9e8413f490626e1572e7fd09825db39c

Files

Oliver Eyton-Williams 61460c8601 fix: insert blank line after ```

search and replace ```\n< with ```\n\n< to ensure there's an empty line
before closing tags

2020-08-16 04:45:20 +05:30

5.8 KiB

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id, title, challengeType, isRequired, videoUrl, localeTitle

id	title	challengeType	isRequired	videoUrl	localeTitle
5a24c314108439a4d4036179	Create a Controlled Form	6	false		创建受控表格

Description

最后一个挑战表明，React可以控制input和textarea等某些元素的内部状态，这使得它们成为受控组件。这也适用于其他表单元素，包括常规HTML form元素。

Instructions

MyForm组件设置为带有提交处理程序的空form 。提交表单时将调用提交处理程序。我们添加了一个提交表单的按钮。您可以看到它的type设置为submit表明它是控制表单的按钮。在form添加input元素并设置其value和onChange()属性， onChange()一个挑战。然后，您应该完成handleSubmit方法，以便将组件状态属性submit设置为本地state的当前输入值。 注意：您还必须在提交处理程序中调用event.preventDefault() ，以防止将刷新网页的默认表单提交行为。最后，在form之后创建一个h1标记，该form从组件的state呈现submit值。然后，您可以键入表单并单击按钮（或按Enter键），您应该看到您的输入呈现给页面。

Tests

tests:
  - text: <code>MyForm</code>应该返回一个包含<code>form</code>和<code>h1</code>标记的<code>div</code>元素。表单应包含<code>input</code>和<code>button</code> 。
    testString: assert((() => { const mockedComponent = Enzyme.mount(React.createElement(MyForm)); return (mockedComponent.find('div').children().find('form').length === 1 && mockedComponent.find('div').children().find('h1').length === 1 && mockedComponent.find('form').children().find('input').length === 1 && mockedComponent.find('form').children().find('button').length === 1) })());
  - text: <code>MyForm</code>的状态应该使用<code>input</code>和<code>submit</code>属性初始化，两者都设置为空字符串。
    testString: assert(Enzyme.mount(React.createElement(MyForm)).state('input') === '' && Enzyme.mount(React.createElement(MyForm)).state('submit') === '');
  - text: 输入<code>input</code>元素应该更新组件状态的<code>input</code>属性。
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: '''' }); return waitForIt(() => mockedComponent.state(''input''))}; const _2 = () => { mockedComponent.find(''input'').simulate(''change'', { target: { value: ''TestInput'' }}); return waitForIt(() => ({ state: mockedComponent.state(''input''), inputVal: mockedComponent.find(''input'').props().value }))}; const before = await _1(); const after = await _2(); assert(before === '''' && after.state === ''TestInput'' && after.inputVal === ''TestInput''); }; '
  - text: 提交表单应该运行<code>handleSubmit</code> ，它应该将<code>submit</code>属性设置为等于当前输入的状态。
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: '''' }); mockedComponent.setState({submit: ''''}); mockedComponent.find(''input'').simulate(''change'', {target: {value: ''SubmitInput''}}); return waitForIt(() => mockedComponent.state(''submit''))}; const _2 = () => { mockedComponent.find(''form'').simulate(''submit''); return waitForIt(() => mockedComponent.state(''submit''))}; const before = await _1(); const after = await _2(); assert(before === '''' && after === ''SubmitInput''); };'
  - text: <code>h1</code>标头应该从组件的状态呈现<code>submit</code>字段的值。
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: '''' }); mockedComponent.setState({submit: ''''}); mockedComponent.find(''input'').simulate(''change'', {target: {value: ''TestInput''}}); return waitForIt(() => mockedComponent.find(''h1'').text())}; const _2 = () => { mockedComponent.find(''form'').simulate(''submit''); return waitForIt(() => mockedComponent.find(''h1'').text())}; const before = await _1(); const after = await _2(); assert(before === '''' && after === ''TestInput''); }; '

Challenge Seed

class MyForm extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      input: ",
      submit: "
    };
    this.handleChange = this.handleChange.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }
  handleChange(event) {
    this.setState({
      input: event.target.value
    });
  }
  handleSubmit(event) {
    // change code below this line

    // change code above this line
  }
  render() {
    return (
      <div>
        <form onSubmit={this.handleSubmit}>
          { /* change code below this line */ }

          { /* change code above this line */ }
          <button type='submit'>Submit!</button>
        </form>
        { /* change code below this line */ }

        { /* change code above this line */ }
      </div>
    );
  }
};

After Test

console.info('after the test');

Solution

// solution required

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