1.安装

yarn add react-transition-group

2.使用

参数描述

 <CSSTransition in={this.state.show} timeout={1000} classNames="fade" unmountOnExit onEntered={(el) => { el.style.color = 'blue' }}  appear={true}>
                    <div>
                        hello
                   </div>
 </CSSTransition>
// 1 unmountOnExit   隐藏之后会把 DOM 删除，设置unmountOnExit是否要在退出完成后卸载组件

 //2  onEntered={(el) => { el.style.color = 'blue' }}    动画进入完成之后 ，变成蓝色
//  el 指的是   <CSSTransition> </CSSTransition> 包裹的div元素
等价于 
.fade-enter-done {
  opacity: 1;
  color: blue;
}

// 3 希望 hello 第一次展示的时候也有动画效果， 设置  appear={true} 
.fade-enter,
.fade-appear {
  opacity: 0;
}
.fade-enter-active,
.fade-appear-active {
  opacity: 1;
  transition: opacity 1s ease-in;
}

3.全部代码

image.png

App.js

import React, { Component, Fragment } from 'react';
import { CSSTransition } from 'react-transition-group';
import './style.css'

class App extends Component {
    constructor(props) {
        super(props);
        this.state = {
            show: true
        }
        this.handleToggole = this.handleToggole.bind(this)
    }
    render() {
        return (
            <Fragment>
                <CSSTransition in={this.state.show} timeout={1000} classNames="fade" unmountOnExit onEntered={(el) => { el.style.color = 'blue' }} appear={true}>
                    <div>
                        hello
                   </div>
                </CSSTransition>

                <button onClick={this.handleToggole}>toggle</button>
            </Fragment>

        )
    }
    handleToggole() {
        this.setState({
            show: this.state.show ? false : true
        })
    }
}
export default App

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App'


ReactDOM.render(
  // <React.StrictMode>
  <App />,
  // {/* </React.StrictMode>, */}
  document.getElementById('root')
);

style.css

.fade-enter,
.fade-appear {
  opacity: 0;
}
.fade-enter-active,
.fade-appear-active {
  opacity: 1;
  transition: opacity 1s ease-in;
}
.fade-enter-done {
  opacity: 1;
  color: red;
}

.fade-exit {
  opacity: 1;
}
.fade-exit-active {
  opacity: 0;
  transition: opacity 1s ease-in;
}
.fade-exit-done {
  opacity: 0;
}