Arpith Siromoney 💬

Animating React Components

A few days ago I talked about server rendering with React Router, and yesterday I talked about using it on the client side to render components based on url path, for example, rendering the home page when the url is ‘/’ and the about page when the url is ‘/about’.

Today’s post is about how you can animate these changes.

Use ReactCSSTransitionGroup

Wrap the components you want to animate in ReactCSSTransitionGroup. Yesterday’s app component now looks like:

import React from 'react';
import ReactCSSTransitionGroup from 'react-addons-css-transition-group';
import Header from './Header';
  
class App extends React.Component {
  render() {
    return (
      <div>
        <Header />
        <ReactCSSTransitionGroup
          transitionName="example"
          transitionEnterTimeout={500}
          transitionLeaveTimeout={300}
        >
          {React.cloneElement(this.props.children, {key: page})}
        </ReactCSSTransitionGroup>
      </div>
    );
  }
}

export default App;

React’s cloneElement() lets you add a key to the child component passed by React Router — this is how React determines which children have entered, left or stayed.

Add CSS Classes

There are a bunch of things you can animate with CSS, these classes use opacity to produce a fade-in effect:

.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 300ms ease-in;
}

That’s about it!

Doing something cool with React? Let me know!