New writing method of react official website animation library (react-transition-group)

# npm
npm install react-transition-group --save

# yarn
yarn add react-transition-group

//自己简单的封装了一个，该有的参数都由了，可以自行粘贴在自己的代码里面去试试。
class Fade extends React.Component {
  constructor(props) {
    super(props);
  }
  done =() => {
    // console.log('结束了')
  }
  addaddEndListener = (node) => { //原生时间transition运动的事件
    node.addEventListener('transitionend', this.done, false);
  }

  // 三个进入状态的事件，可以做你想做的事情
  onEnter = (node, isAppearing) => {
    console.log(isAppearing, 'onEnter')
  }
  onEntering = (node, isAppearing) => {
    console.log(isAppearing, 'onEntering')
  }
  onEntered = (node, isAppearing) => {
    console.log(isAppearing, 'onEntered')
  }

  // 三个退出的状态的事件
  onExit = (node) => {
    console.log('onExit')
  }
  onExiting = () => {
    console.log('onExiting')
  }
  onExited = () => {
    console.log('onExited')
    this.props.self()
  }
  render() {
    const { in: inProp, dur} = this.props;
    const defaultStyle = {
      transition: `transform ${300}ms ease-in-out, opacity ${300}ms ease-in-out`,
      transform: 'translateX(100px)',
      opacity: '0'
    }

    const transitionStyles = {
      entering: { transform: 'translateX(100px)', opacity: '0'},
      entered:  { transform: 'translateX(0px)', opacity: '1' },
      exiting: {transform: 'translateX(0px)', opacity: '1'},
      exited: {transform: 'translateX(0px)', opacity: '0'}
    };
    const duration = {
      enter: 300,
      exit: 300,
    }
    // 上面的都是基本参数，样式的转变以及时间的设定，具体的可以看官网文档
    // 样式也可以写成className 例如<MyComponent className={`fade fade-${status}`} />
    return (
      <Transition 
        onEnter={this.onEnter}
        onEntering={this.onEntering}
        onEntered={this.onEntered}

        onExit={this.onExit}
        onExiting={this.onExiting}
        onExited={this.onExited}

        addEndListener={this.addaddEndListener} 
        in={inProp} 
        unmountOnExit={false} // 为true 代表退出的时候移除dom
        appear={true} // 为true  渲染的时候就直接执行动画，默认false，
        timeout={duration}
      >
        {
          state => {
            console.log(state, '###') //你可以很直观的看到组件加载和卸载时候的状态
            return(
              <p style={{
                ...defaultStyle,
                ...transitionStyles[state]
              }}>
                {this.props.children}
              </p>
            )
          }
        }
      </Transition>
    );
  }
}

entering
entered
exiting
exited

let num = 1;
class Dnd extends React.Component {
  state = {
    ins: true,
    current: 1,
    dom: <p className={l.test}>
            ceshi weizhi {num}
          </p>
  }
  handle = (bool) => {
    this.setState({
      test: !bool
    })
  }
  end = () => {
    const that = this;
    num = num + 1;
    setTimeout(function () {
      that.setState({
        test: true,
        dom: <p className={l.test}>
              888888 {num}
            </p>
      }) 
    }, 500)
    
  }
  render () {
    const { location } = this.props
    const { test } = this.state;
    return (
      <MainLayout location={location}>
        <Button onClick={this.handle.bind(null, this.state.test)}>点击transition</Button>
        <Fade in={this.state.test} self={this.end}>
          {this.state.dom}
        </Fade>
      </MainLayout>
    )
  }
}
// 效果是每次点击按钮都会进行一次进场和出场的动画。也可以自行衍生。

这个组件大概就是这样的，这样适合写一个tab类型的页面，在切换的时候可以展示不同的dom

state  = {
    star: false
}


<Button onClick={this.handleStar.bind(null, star)}>start</Button>
<CSSTransition
  in={star}
  timeout={300}
  classNames="star"
  unmountOnExit
>
  <p className="star">⭐</p>
</CSSTransition>

.star {
    display: inline-block;
    margin-left: 0.5rem;
    transform: scale(1.25);
  }
  .star-enter {
    opacity: 0.01;
    transform: translateY(-100%) scale(0.75);
  }
  .star-enter-active {
    opacity: 1;
    transform: translateY(0%) scale(1.25);
    transition: all 300ms ease-out;
  }
  .star-exit {
    opacity: 1;
    transform: scale(1.25);
  }
  .star-exit-active {
    opacity: 0;
    transform: scale(4);
    transition: all 300ms ease-in;
  }

1、星星显示 对应的class为star-enter star-enter-active 动画走完为star-enter-done
2、星星消失 对应的class为star-exit  star-exit-active 动画走完为star-exit-done

classNames={{
 appear: 'my-appear',
 appearActive: 'my-active-appear',
 enter: 'my-enter',
 enterActive: 'my-active-enter',
 enterDone: 'my-done-enter,
 exit: 'my-exit',
 exitActive: 'my-active-exit',
 exitDone: 'my-done-exit,
}}

class List extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      items: [
        { id: 1, text: 'Buy eggs' },
        { id: 2, text: 'Pay bills' },
        { id: 3, text: 'Invite friends over' },
        { id: 4, text: 'Fix the TV' },
      ]
    }
  }

  render() {
    const { items } = this.state; 
    return (
      <p>
        <TransitionGroup className="todo-list">
          {items.map(({ id, text }) => (
            <CSSTransition
              key={id}
              timeout={500}
              classNames="fade"
            >
              <p>
                <Button
                  onClick={() => {
                    this.setState(state => ({
                      items: state.items.filter(
                        item => item.id !== id
                      ),
                    }));
                  }}
                >
                  &times;
                </Button>
                {text}
              </p>
            </CSSTransition>
          ))}
        </TransitionGroup>
        <Button
          type="button"
          onClick={() => {
            const text = prompt('Enter some text');
            if (text) {
              this.setState(state => ({
                items: [
                  ...state.items,
                  { id: 1123, text },
                ],
              }));
            }
          }}
        >
          Add Item
        </Button>
      </p>
    );
  }
}

.fade-enter {
    opacity: 0.01;
  }
  .fade-enter-active {
    opacity: 1;
    transition: opacity 500ms ease-in;
  }
  .fade-exit {
    opacity: 1;
  }
  .fade-exit-active {
    opacity: 0.01;
    transition: opacity 500ms ease-in;
  }

1、component  default 'p' 也就是TransitionGroup渲染出来的标签为p，也可以就行更改，例如component="span" 渲染出来的就是span标签了
2、children 相当于你给的组件，可以是字符串或者自定义组件等。
3、appear  写在TransitionGroup里面相当于开启或者禁止里面的Transition || CSSTransition 方便写的作用