Animations with ReactTransitionGroup
When to use ReactTransitionGroup
Most React projects with animations use ReactCSSTransitionGroup. While nearly any animation can be done in CSS, CSS animations tend to be more difficult to maintain once they reach a certain level of complexity.
Starting off simple
Let’s start with a page that has a div that’s conditionally shown based on the flag shouldShowBox, we’ll leave transition groups out for now.
When shouldShowBox is true, the “.box” is visible, and when it’s false, it’s not.
npm install react-addons-transition-group
Then import to our file via
import TransitionGroup from 'react-addons-transition-group';
Now, add the TransitionGroup to our `Page` component’s render so that it becomes:
To give components inside the TransitionGroup the flexibility of having differing animations, the TransitionGroup does not define animations itself, but will call the corresponding enter or leave animation hooks on its child components when the child components are added or removed.
You will typically only need these two lifecycle hooks -
Called on components that are added to an existing TransitionGroup, at the same time as the component’s componentDidMount.
Not called on the initial render of the entire TransitionGroup (e.g. when a page is initially loaded), for that you’d want componentWillAppear
Called on components that have been removed from a TransitionGroup. This is called before componentWillUnmount, and componentWillUnmount will not trigger until the callback here is called.
Note that you must call the supplied callbacks after your animation ends, otherwise your component will enter but not leave, or leave but not enter.
See the official docs for detailed info on all the animation lifecycle hooks.
Because ReactTransitionGroup relies on those hooks to exist, and a div doesn’t have those hooks defined, we’ll have to first move our <div className=”box”/> into its own component:
Then add in the animation lifecycle hooks. We’ll be using GSAP’s TweenMax for animation.
For those unfamiliar with TweenMax, here’s the function signature of fromTo:
Now we have a simple animation using ReactTransitionGroup!
The next few parts will be on reusing animations via higher-order components, integrating with react-router, and coordinating nested transitions.
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