17、ReactJS - 动画

在本教程中我们将学习如何用 React 来制作淡入(fade in)淡出(fade out)动画( Animations )。

首先,先安装 React CSS Transitions Group 组件

npm install react-addons-css-transition-group

因为我们的淡入淡出动画使用的是 CSS transitions and animations

其次,添加应用的样式表文件

先创建一个 css目录,再添加 style.css 文件,完成后目录结构如下

|--css
|  |-- style.css

接着,把创建好的 style.css 链接到 index.html

<Linkrel = "stylesheet" href = "css/style.css">

再次,给加载列表添加淡入进场动画

1、 新建一个ReactCSSTransitionGroup组件用来包裹需要动画的html元素;
2、 然后设置transitionAppear,transitionAppearTimeout,transitionEnter,transitionLeave属性.;

App.jsx

import React from 'react';
var ReactCSSTransitionGroup = require('react-addons-css-transition-group');

class App extends React.Component {

   render() {
      return (
         <div>
            <ReactCSSTransitionGroup transitionName = "example"
               transitionAppear = {true} transitionAppearTimeout = {500}
               transitionEnter = {false} transitionLeave = {false}>

               <h1>My Element...</h1>
            </ReactCSSTransitionGroup>
         </div>      
      );
   }
}

export default App;

创建 main.js

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

ReactDOM.render(<App />, document.getElementById('app'));

使用 CSS animation 非常简单

完善样式 css/style.css

.example-appear {
   opacity: 0.01;
}

.example-appear.example-appear-active {
   opacity: 1;
   transition: opacity 500ms ease-in;
}

运行我们的应用,我们的元素就会有 淡入 动画  

最后,完善进场动画和退场动画

接下来我们给新增操作添加进场动画,删除操作添加退场动画

App.jsx

import React from 'react';
var ReactCSSTransitionGroup = require('react-addons-css-transition-group');

class App extends React.Component {

   constructor(props) {
      super(props);

      this.state = {
         items: ['Item 1...', 'Item 2...', 'Item 3...', 'Item 4...']
      }

      this.handleAdd = this.handleAdd.bind(this);
   };

   handleAdd() {
      var newItems = this.state.items.concat([prompt('Create New Item')]);
      this.setState({items: newItems});
   }

   handleRemove(i) {
      var newItems = this.state.items.slice();
      newItems.splice(i, 1);
      this.setState({items: newItems});
   }

   render() {
      var items = this.state.items.map(function(item, i) {
         return (
            <div key = {item} onClick = {this.handleRemove.bind(this, i)}>
               {item}
            </div>
         );

      }.bind(this));

      return (
         <div>      
            <button onClick = {this.handleAdd}>Add Item</button>

            <ReactCSSTransitionGroup transitionName = "example" 
               transitionEnterTimeout = {500} transitionLeaveTimeout = {500}>
               {items}
            </ReactCSSTransitionGroup>
         </div>
      );
   }
}

export default App;

main.js

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

ReactDOM.render(<App />, document.getElementById('app'));

css/style.css

.example-enter {
   opacity: 0.01;
}

.example-enter.example-enter-active {
   opacity: 1;
   transition: opacity 500ms ease-in;
}

.example-leave {
   opacity: 1;
}

.example-leave.example-leave-active {
   opacity: 0.01;
   transition: opacity 500ms ease-in;
}

运行我们的应用并单击 添加 按钮,你就能看到我们的进场和退场动画

  输入名字,然后单击 添加按钮, 我们添加的 新公司 就会淡入.  

现在我们来删除 Item 3...Item 3 这个元素就会淡出