react中使用Pure Component

import React, { Component, PureComponent } from 'react';
import logo from './logo.svg';
import './App.css';

class Temp extends PureComponent {
  render() {
    console.log('render Temp');
    return (
      
{ this.props.val }
    );
  }
}

class App extends Component {
  state = {
    val: 1
  }

  componentDidMount() {
    setInterval(() => {
      this.setState({
        val: 1
      })
    }, 2000)
  }

  // shouldComponentUpdate(nextProps, nextState) {
  //   console.log('nextState', nextState);
  //   console.log('current state', this.state);
  //   return (
  //     this.state.val === nextState.val ? false : true
  //   )
  // }

  render() {
    console.log('render App');
    return (
      

        

          
          
Welcome to React
        
        

          To get started, edit src/App.js and save to reload.
        
        
      
    );
  }
}

export default App;