React.js之props

這次帶給大家React.js之props，使用React.js的props注意事項有哪些，下面就是實戰案例，一起來看一下。

父元件傳值給子元件

<Son userid={123}/>

在Son元件接收父元件傳遞過來的值

<p>接收到的父页面的属性 -- userid: {this.props.userid} username:{this.props.username}</p>

當然也可以在Son頁面設定傳遞參數的類型和預設值

// 给属性设置类型BodyIndex.propTypes = {    // isRequired 必须的参数
    userid: React.PropTypes.number.isRequired,
    username: React.PropTypes.string
}// 设置默认值BodyIndex.defaultProps = {
    username: '哈哈'}

設定類型具體參考官方文件

MyComponent.propTypes = { // You can declare that a prop is a specific JS primitive. By default, these
 // are all optional.
 optionalArray: PropTypes.array, optionalBool: PropTypes.bool, optionalFunc: PropTypes.func, optionalNumber: PropTypes.number, optionalObject: PropTypes.object, optionalString: PropTypes.string, optionalSymbol: PropTypes.symbol, // Anything that can be rendered: numbers, strings, elements or an   array// (or fragment) containing these types.optionalNode: PropTypes.node,// A React element.optionalElement: PropTypes.element, // You can also declare that a prop is an instance of a class. This uses
  // JS's instanceof operator.
  optionalMessage: PropTypes.instanceOf(Message),  // You can ensure that your prop is limited to specific values by treating
  // it as an enum.
  optionalEnum: PropTypes.oneOf(['News', 'Photos']),  // An object that could be one of many types
  optionalUnion: PropTypes.oneOfType([
    PropTypes.string,
    PropTypes.number,
    PropTypes.instanceOf(Message)
  ]),  // An array of a certain type
  optionalArrayOf: PropTypes.arrayOf(PropTypes.number),  // An object with property values of a certain type
  optionalObjectOf: PropTypes.objectOf(PropTypes.number),  // An object taking on a particular shape
  optionalObjectWithShape: PropTypes.shape({    color: PropTypes.string,    fontSize: PropTypes.number
  }),  // You can chain any of the above with `isRequired` to make sure a warning
  // is shown if the prop isn't provided.
  requiredFunc: PropTypes.func.isRequired,  // A value of any data type
  requiredAny: PropTypes.any.isRequired,  // You can also specify a custom validator. It should return an Error
  // object if the validation fails. Don't `console.warn` or throw, as this
  // won't work inside `oneOfType`.
  customProp: function(props, propName, componentName) {    if (!/matchme/.test(props[propName])) {      return new Error(        'Invalid prop `' + propName + '` supplied to' +        ' `' + componentName + '`. Validation failed.'
      );
    }
  },  // You can also supply a custom validator to `arrayOf` and     `objectOf`.
  // It should return an Error object if the validation fails. The validator
  // will be called for each key in the array or object. The first two
  // arguments of the validator are the array or object itself, and the
  // current item's key.
  customArrayProp: PropTypes.arrayOf(function(propValue, key,       componentName, location, propFullName) {    if (!/matchme/.test(propValue[key])) {      return new Error(        'Invalid prop `' + propFullName + '` supplied to' +        ' `' + componentName + '`. Validation failed.'
      );
    }
  })
 };

Son元件把從父元件傳遞過來的屬性傳遞到孫子元件
透過展開運算符{...this.props},把從父組件傳遞過來的屬性,全部傳遞給自己的子組件(孫子組件)
id={1234} 為Son組件自己傳遞給孫子組件的屬性

<GrandSon {...this.props} id={1234}/>

在孫子元件呼叫從Son元件傳遞過來的屬性

<p>{this.props.userid} {this.props.username} {this.props.id}</p>

refs: 是存取到元件內部DOM 節點唯一可靠的方法

給標籤新增ref

<input ref=&#39;submitButton&#39; type="button" value=&#39;提交&#39; onClick={() => this.changeUserInfo(99)}/>

當想要取得該dom時,透過this.refs.xxx取得

this.refs.submitButton.style.color = 'red';

注意:

不要在render 或render 之前對Refs 進行呼叫;

不要濫用Refs,能不使用,就不要使用!!!

相信看了本文案例你已經掌握了方法，更多精彩請關注php中文網其它相關文章！

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