React.js之props

这次给大家带来React.js之props，使用React.js的props注意事项有哪些，下面就是实战案例，一起来看一下。

父组件向子组件传值

<Son userid={123}/>

在Son组件接收父组件传递过来的值

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

当然也可以在Son页面设置传递参数的类型和默认值

// 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'}

设置类型具体参考官方文档

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组件把从父组件传递过来的属性传递到孙子组件
通过展开运算符{...this.props},把从父组件传递过来的属性,全部传递给自己的子组件(孙子组件)
id={1234} 为Son组件自己传递给孙子组件的属性

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

在孙子组件调用从Son组件传递过来的属性

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

refs: 是访问到组件内部 DOM 节点唯一可靠的方法

给标签添加ref

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

当想要获取该dom时,通过this.refs.xxx获取

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

注意:

不要在 render 或 render 之前对 Refs 进行调用;

不要滥用 Refs,能不使用,就不要使用!!!

相信看了本文案例你已经掌握了方法，更多精彩请关注其它相关文章！

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