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

`ReactTransitions` 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](http://www.nganimate.org/) library.

## Getting Started

`ReactTransitionGroup` 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.

```javascript{22-24}
/** @jsx React.DOM */

var ReactTransitionGroup = React.addons.TransitionGroup;

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={i} onClick={this.handleRemove.bind(this, i)}>
          {item}
        </div>
      );
    }.bind(this));
    return (
      <div>
        <div><button onClick={this.handleAdd} /></div>
        <ReactTransitionGroup transitionName="example">
          {items}
        </ReactTransitionGroup>
      </div>
    );
  }
});
```

In this component, when a new item is added to `ReactTransitionGroup` 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:

```css
.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 `ReactTransitionGroup` 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 `ReactTransitionGroup` keeps your DOM elements on the page until the animation completes. Try adding this CSS:

```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 `ReactTransitionGroup` waits for an animation to complete before removing your DOM node. You can add `transitionEnter={false}` or `transitionLeave={false}` props to `ReactTransitionGroup` to disable these animations.

## 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>`:

```javascript{3}
<ReactTransitionGroup
  transitionName="example"
  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!
