react项目中实现购物车的增减

import React, { Component } from 'react'

export default class App extends Component {

  state={

    count:5

  }

  f1=()=>{

    let count=this.state.count-1

    this.setState({count:count},()=>{})

  }

  f2=()=>{

    let count=this.state.count+1

    this.setState({count:count},()=>{})

  }

  render() {

    return (

      <>

        <button onClick={this.f1}>-</button>

        <span>{this.state.count}</span>

        <button onClick={this.f2}>+</button>

      </>

    )

  }

}