React CSSTransition not ananiming

Question

我想为我的Web应用程序中的一个盒子（淡入，淡出）设置动画。我为此使用react-transition-group。但是不知何故，动画无法正常工作。代码

import React from 'react';
import ReactDOM from 'react-dom';
import { CSSTransition } from 'react-transition-group';
import Modal from 'react-modal';

import './styles.css';

class Example extends React.Component {
  state = {
    isOpen: false,
  };

  toggleModal = () => {
    this.setState(prevState => ({
      isOpen: !prevState.isOpen,
    }));
  };
  render() {
    const modalStyles = {
      overlay: {
        backgroundColor: '#ffffff',
      },
    };
    return (
      <div>
        <button onClick={this.toggleModal}>
          Open Modal
        </button>
        <CSSTransition
          in={this.state.isOpen}
          timeout={300}
          classNames="dialog"
        >
          <Modal
            isOpen={this.state.isOpen}
            style={modalStyles}
          >
            <button onClick={this.toggleModal}>
              Close Modal
            </button>
            <div>Hello World</div>
          </Modal>
        </CSSTransition>
      </div>
    );
  }
}

CSS：

.dialog-enter {
  opacity: 0;
  transition: opacity 500ms linear;
}
.dialog-enter-active {
  opacity: 1;
}
.dialog-exit {
  opacity: 0;
}
.dialog-exit-active {
  opacity: 1;
}

.box {
  width: 200px;
  height: 100vh;
  background: blue;
  color: white;
}

Here是工作代码。单击“打开模态”以打开模态，然后单击“切换框”以打开/关闭我要设置动画的框。

Answer 1

您必须完全相信对CSSTransition的安装/卸载。

  <CSSTransition
    in={this.state.boxVisible}
    timeout={1500}
    classNames="dialog"
    unmountOnExit
  >
    <div>
      <div className="box">Box</div>
    </div>
  </CSSTransition>

参见此处：https://codesandbox.io/s/csstransition-component-9obbb