App.css
.show{
opacity: 1;
transition: all 1s ease-in;
}

.hide{
opacity: 0;
transition: all 1s ease-in;
}
App.jsx文件
import React, { Component, Fragment } from 'react’
import ‘./App.css’

export default class App extends Component {
state = { show: true }
handleToggole = () => {
this.setState({
show: this.state.show ? false : true
})
}
render() {
const { show } = this.state
return (

<div className={show ? ‘show’ : ‘hide’}>hello
toggle

)
}
}