React 避免 setState 的合并调用特性

index.js

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

class ANumber extends React.Component {
  constructor() {
    super()
    this.state = {
      num: 0,
    }
  }
  componentDidMount() {
    this.setState(state => ({ num: state.num + 1 }))
    this.setState(state => ({ num: state.num + 1 }))
    this.setState(state => ({ num: state.num + 1 }))
    this.setState(state => ({ num: state.num + 1 }))
    this.setState(state => ({ num: state.num + 1 }))
    this.setState(state => ({ num: state.num + 1 }))
    // 展示 6，避免了 setState 合并调用特性
  }
  render() {
    return <h1>{this.state.num}</h1>
  }
}

ReactDOM.render(<ANumber />, document.getElementById('root'))