React組件傳值方式總結

1. 子組件向父組件傳值

父組件Header:

import Nav from 'Nav.js';
class Header extends React.Component {
  constructor(props) {
    super(props);
    this.state = {

    }
    this.callbackForNav = this.callbackForNav.bind(this);
  }
  callbackForNav({ selectedTopChannelOrder, selectedSubChannelOrder, selectedTopChannelName, selectedSubChannelName }) {
    this.setState({ 
      selectedTopChannelOrder, 
      selectedSubChannelOrder, 
      selectedTopChannelName, 
      selectedSubChannelName 
    })
  }
  render() {
    return (<Nav channels={navChannelData} dynamicnav={dynamicNav}  defaultSelectedTopChannelOrder={navDefaultTopOrder} defaultSelectedSubChannelOrder={navDefaultSubOrder} callbackFunc={this.callbackForNav} sticky="top" />)
  }
}

子組件Nav:

class Nav extends React.Component {
  constructor() {
    this.state = {
      selectedTopChannelOrder:0, 
      selectedSubChannelOrder:-1,
      selectedTopChannelName: "", 
      selectedSubChannelName:""
    }
  }
  static propTypes = {
    callbackFunc: PropTypes.func
  }
  componentDidMount() {
    const {selectedTopChannelOrder, selectedSubChannelOrder, selectedTopChannelName, selectedSubChannelName} = this.state;
    this.props.callbackFunc({selectedTopChannelOrder, selectedSubChannelOrder, selectedTopChannelName, selectedSubChannelName}) 
  }
  clickSubChannel() {
     this.setState({
        selectedTopChannelOrder: topOrder,
        selectedTopChannelName: topName,
        selectedSubChannelOrder: subOrder,
        selectedSubChannelName: subName
    });
    this.props.callbackFunc({
        selectedTopChannelOrder: topOrder,
        selectedTopChannelName: topName,
        selectedSubChannelOrder: subOrder,
        selectedSubChannelName: subName
    });
  }

  render() {
    return (...)
  }
}

2. 跨級組件傳值

利用context

父組件:

class List extends React.Component {
  static childContextType = {
    color:PropTypes.string
  }

  getChildContext() {
    return {
      color:'red'
    }
  }
  render() {
    return (...)
  }
}

子組件:

class ListItem extends React.Component {
  static contextTypes = {
    color:PropTypes.string
  }

  render(){
    return (
      <li style={{background:this.context.color}}>someword</li>
    )
  }
}

3. 無嵌套關係的組件傳值

import {EventEmitter} from 'events';

const emitter = new EventEitter();

class A extends React.Component {
  clickHandler(data,e) {
    this.setState({
      ...
    });
    emitter.emit('theclick', data);
  }
  render() {
    const data = 'xxx';
    return (<div onClick={this.clickHandler.bind(this, data)} />)
  }
}

App containing A and B:

import {EventEmitter} from 'events';

const emitter = new EventEitter();

class App extends React.Component {
  componentDidMount() {
    this.listenerForTheClick = emitter.on('theclick', (data) => {
      this.setState({
        propForB: data;
      })
    })
  }
  componentWillUnmount() {
    emitter.remove(this.listenerForTheClick);
  }

  render() {
    return (
      <B someprop={this.state.propForB} />
      <A />
    )
  }
}