React Refs 簡單演示

React 支持一種非常特殊的屬性 Ref ，可以用來綁定到 render() 輸出的任何組件上

import React, { Component } from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import * as serviceWorker from './serviceWorker';

class Focus extends Component{
  constructor(props){
    super(props);
    this.focusFn=this.focusFn.bind(this);
  }

  focusFn(){
    this.refs.myInput.focus();
  }

  render(){
    return(
      <div>
        <input type="text" ref="myInput" />
        <br/>
        <button onClick={this.focusFn}>點我</button>
      </div>
    )
  }
}

  ReactDOM.render(
    <div>
       <Focus />
    </div>,
    document.getElementById('example')
  );

serviceWorker.unregister();