React8 props的children校验默认值

Posted 2022-12-08 阿拉的梦想

【React】8 props的children、校验、默认值

• 1. props.children 属性
• 2. props 校验
• 3. props默认值

1. props.children 属性

• children 属性：表示组件标签的子节点。当组件标签有子节点时，props就会有该属性。
• chidren 属性与普通的props一样，值可以是任意值（文本、React元素、组件，甚至是函数）

demo：

import React from 'react'
import ReactDOM from 'react-dom/client'


//组件1
class  User extends React.Component 


  render() 
    return (
      // 传入非函数children
      // <Node1>hello</Node1>
      // <Node1><button>hello</button></Node1>

      //传入函数children
      <Node1>
        () => console.log("函数1")
      </Node1>
    )
  



//组件
const Node1 = (props) => 

  //使用函数children
  props.children()
  return (
    //使用非函数children
    // <div>node1--props.children</div>

    <div>node1--</div>
  )



const root = ReactDOM.createRoot(document.getElementById("root"))
root.render(<User />)

效果：

2. props 校验

使用步骡

1. 安装包 prop-types ( yarn add prop-types / npm i prop-types )
2. 导入 prop-types包，import PropTypes from 'prop-types'；
3. 使用组件名.propTypes = 来给组件的props添加校验规则
4. 按验规见面过 PropTypes象来指定

import React from 'react'
import ReactDOM from 'react-dom/client'
//导入校验包
import PropTypes from 'prop-types'

//组件
const Node1 = (props) => 
  console.log(props)
  return (
    <div>node1--props.colors[0]</div>
  )


//添加校验规则
Node1.propTypes = 
  colors: PropTypes.array


const root = ReactDOM.createRoot(document.getElementById("root"))
// root.render(<Node1 colors=["red", "blue"] />)
root.render(<Node1 colors="qq" />)

效果：
传入错误参数时，会提示类型错误

常用验证规则：
若是必填则后面加.isRequired

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.
//验证是否为节点
  optionalNode: PropTypes.node,
 
//验证是否为元素
  // A React element (ie. <MyComponent />).
  optionalElement: PropTypes.element,
 
//验证是否为元素类型
  // A React element type (ie. MyComponent).
  optionalElementType: PropTypes.elementType,
 
//验证是否为另一个类的实例
  // You can also declare that a prop is an instance of a class. This uses
  // JS's instanceof operator.
  optionalMessage: PropTypes.instanceOf(Message),
 
//验证传入值是否在给定范围
  // You can ensure that your prop is limited to specific values by treating
  // it as an enum.
  optionalEnum: PropTypes.oneOf(['News', 'Photos']),
 
//验证传入类型是否在给定范围
  // 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),
 
  // You can chain any of the above with `isRequired` to make sure a warning
  // is shown if the prop isn't provided.
 
  // An object taking on a particular shape
  optionalObjectWithShape: PropTypes.shape(
    optionalProperty: PropTypes.string,
    requiredProperty: PropTypes.number.isRequired
  ),
 
  // An object with warnings on extra properties
  optionalObjectWithStrictShape: PropTypes.exact(
    optionalProperty: PropTypes.string,
    requiredProperty: PropTypes.number.isRequired
  ),
 
  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`.
//回调函数：自定义验证规则
  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.'
      );
    
  )
;

3. props默认值

指定 props 的默认值， 这个方法只有浏览器编译以后才会生效

class HandsomeBoy extends Component
  // 设置默认值
  //defaultProps 可以为 Class 组件添加默认 props,基于 static 的写法
  static defaultProps = 
    name:'pyq'
  
  constructor(props)
    super(props)
  
  render()
  return <section>this.props.name</section>
  

指定 props 的默认值，这个方法会一直生效

class Age extends Component
  
  render()
    return <section>this.props.name</section>

  

// 默认值的第二种,指定 props 的默认值，这个方法会一直生效
Age.defaultProps = 
    name:18