react.dev/docs/09.1-animation.md

id	title	layout	permalink	prev	next
animation	Animation	docs	animation.html	addons.html	two-way-binding-helpers.html

React provides a ReactTransitionGroup addon component as a low-level API for animation, and a ReactCSSTransitionGroup for easily implementing basic CSS animations and transitions.

High-level API: ReactCSSTransitionGroup

ReactCSSTransitionGroup is based on ReactTransitionGroup and is an easy way to perform CSS transitions and animations when a React component enters or leaves the DOM. It's inspired by the excellent ng-animate library.

Getting Started

ReactCSSTransitionGroup is the interface to ReactTransitions. This is a simple element that wraps all of the components you are interested in animating. Here's an example where we fade list items in and out.

/** @jsx React.DOM */

var ReactCSSTransitionGroup = React.addons.CSSTransitionGroup;

var TodoList = React.createClass({
  getInitialState: function() {
    return {items: ['hello', 'world', 'click', 'me']};
  },
  handleAdd: function() {
    var newItems =
      this.state.items.concat([prompt('Enter some text')]);
    this.setState({items: newItems});
  },
  handleRemove: function(i) {
    var newItems = this.state.items;
    newItems.splice(i, 1)
    this.setState({items: newItems});
  },
  render: function() {
    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>
        <div><button onClick={this.handleAdd} /></div>
        <ReactCSSTransitionGroup transitionName="example">
          {items}
        </ReactCSSTransitionGroup>
      </div>
    );
  }
});

In this component, when a new item is added to ReactCSSTransitionGroup it will get the example-enter CSS class and the example-enter-active CSS class added in the next tick. This is a convention based on the transitionName prop.

You can use these classes to trigger a CSS animation or transition. For example, try adding this CSS and adding a new list item:

.example-enter {
  opacity: 0.01;
  transition: opacity .5s ease-in;
}

.example-enter.example-enter-active {
  opacity: 1;
}

You'll notice that when you try to remove an item ReactCSSTransitionGroup keeps it in the DOM. If you're using an unminified build of React with add-ons you'll see a warning that React was expecting an animation or transition to occur. That's because ReactCSSTransitionGroup keeps your DOM elements on the page until the animation completes. Try adding this CSS:

.example-leave {
  opacity: 1;
  transition: opacity .5s ease-in;
}

.example-leave.example-leave-active {
  opacity: 0.01;
}

Disabling Animations

You can disable animating enter or leave animations if you want. For example, sometimes you may want an enter animation and no leave animation, but ReactCSSTransitionGroup waits for an animation to complete before removing your DOM node. You can add transitionEnter={false} or transitionLeave={false} props to ReactCSSTransitionGroup to disable these animations.

Low-level API: ReactTransitionGroup

ReactTransitionGroup is the basis for animations. When children are declaratively added or removed from it (as in the example above) special lifecycle hooks are called on them.

componentWillEnter(callback)

This is called at the same time as componentDidMount() for components added to an existing TransitionGroup. It will block other animations from occurring until callback is called. It will not be called on the initial render of a TransitionGroup.

componentDidEnter()

This is called after the callback function that was passed to componentWillEnter is called.

componentWillLeave(callback)

This is called when the child has been removed from the ReactTransitionGroup. Though the child has been removed, ReactTransitionGroup will keep it in the DOM until callback is called.

componentDidLeave()

This is called when the willLeave callback is called (at the same time as componentWillUnmount).

Rendering a Different Component

By default ReactTransitionGroup renders as a span. You can change this behavior by providing a component prop. For example, here's how you would render a <ul>:

<ReactTransitionGroup component={React.DOM.ul}>
  ...
</ReactTransitionGroup>

Every DOM component is under React.DOM. However, component does not need to be a DOM component. It can be any React component you want; even ones you've written yourself!