react之shouldComponentUpdate簡單定制數據更新

import React from 'react'

class Demo extends React.Component{
  constructor(props){
    super(props)
    this.state={count:1}
    this.handleClick=this.handleClick.bind(this)
  }
  handleClick(){
    this.setState({count:this.state.count+1})
  }
  shouldComponentUpdate(){
    if(this.state.count%5==0){

      return true
    }
    return false
  }
  render(){
    return (
      <div>
        {this.state.count}<br />
        <button onClick={this.handleClick}>點擊</button>
      </div>

    )
  }
}
export default Demo

只有當count等於5時，視圖上才會更新數據