Transition

The Transition component lets you describe a transition from one component state to another over time with a simple declarative API. Most commonly it's used to animate the mounting and unmounting of a component, but can also be used to describe in-place transition states as well.

Note: Transition is a platform-agnostic base component. If you're using transitions in CSS, you'll probably want to use CSSTransition instead. It inherits all the features of Transition, but contains additional features necessary to play nice with CSS transitions (hence the name of the component).

By default the Transition component does not alter the behavior of the component it renders, it only tracks "enter" and "exit" states for the components. It's up to you to give meaning and effect to those states. For example we can add styles to a component when it enters or exits:

import { Transition } from 'react-transition-group';

const duration = 300;

const defaultStyle = {
  transition: `opacity ${duration}ms ease-in-out`,
  opacity: 0,
}

const transitionStyles = {
  entering: { opacity: 1 },
  entered:  { opacity: 1 },
  exiting:  { opacity: 0 },
  exited:  { opacity: 0 },
};

const Fade = ({ in: inProp }) => (
  <Transition in={inProp} timeout={duration}>
    {state => (
      <div style={{
        ...defaultStyle,
        ...transitionStyles[state]
      }}>
        I'm a fade Transition!
      </div>
    )}
  </Transition>
);

There are 4 main states a Transition can be in:

'entering'
'entered'
'exiting'
'exited'

Transition state is toggled via the in prop. When true the component begins the "Enter" stage. During this stage, the component will shift from its current transition state, to 'entering' for the duration of the transition and then to the 'entered' stage once it's complete. Let's take the following example (we'll use the useState hook):

function App() {
  const [inProp, setInProp] = useState(false);
  return (
    <div>
      <Transition in={inProp} timeout={500}>
        {state => (
          // ...
        )}
      </Transition>
      <button onClick={() => setInProp(true)}>
        Click to Enter
      </button>
    </div>
  );
}

When the button is clicked the component will shift to the 'entering' state and stay there for 500ms (the value of timeout) before it finally switches to 'entered'.

When in is false the same thing happens except the state moves from 'exiting' to 'exited'.

Props

`nodeRef`

A React reference to DOM element that need to transition: https://stackoverflow.com/a/51127130/4671932

When nodeRef prop is used, node is not passed to callback functions (e.g. onEnter) because user already has direct access to the node.
When changing key prop of Transition in a TransitionGroup a new nodeRef need to be provided to Transition with changed key prop (see test/CSSTransition-test.js).

type: shape

`children`

A function child can be used instead of a React element. This function is called with the current transition status ('entering', 'entered', 'exiting', 'exited'), which can be used to apply context specific props to a component.

<Transition in={this.state.in} timeout={150}>
  {state => (
    <MyComponent className={`fade fade-${state}`} />
  )}
</Transition>

type: Function | element

required

`in`

Show the component; triggers the enter or exit states

type: boolean

default: false

`mountOnEnter`

By default the child component is mounted immediately along with the parent Transition component. If you want to "lazy mount" the component on the first in={true} you can set mountOnEnter. After the first enter transition the component will stay mounted, even on "exited", unless you also specify unmountOnExit.

type: boolean

default: false

`unmountOnExit`

By default the child component stays mounted after it reaches the 'exited' state. Set unmountOnExit if you'd prefer to unmount the component after it finishes exiting.

type: boolean

default: false

`appear`

By default the child component does not perform the enter transition when it first mounts, regardless of the value of in. If you want this behavior, set both appear and in to true.

Note: there are no special appear states like appearing/appeared, this prop only adds an additional enter transition. However, in the <CSSTransition> component that first enter transition does result in additional .appear-* classes, that way you can choose to style it differently.

type: boolean

default: false

`enter`

Enable or disable enter transitions.

type: boolean

default: true

`exit`

Enable or disable exit transitions.

type: boolean

default: true

`timeout`

The duration of the transition, in milliseconds. Required unless addEndListener is provided.

You may specify a single timeout for all transitions:

timeout={500}

or individually:

timeout={{
 appear: 500,
 enter: 300,
 exit: 500,
}}

appear defaults to the value of enter
enter defaults to 0
exit defaults to 0

type: number | { enter?: number, exit?: number, appear?: number }

`addEndListener`

Add a custom transition end trigger. Called with the transitioning DOM node and a done callback. Allows for more fine grained transition end logic. Timeouts are still used as a fallback if provided.