TransitionGroup

TransitionGroup is a sound answer to <ReactTransitionGroup /> and any wishlist you might have had for it. We suggest you become familiar with it and its higher level CSS-oriented counterpart first to truly understand TransitionGroups's benefits:

• ReactCSSTransitionGroup
• ReactTransitionGroup

The biggest problem TransitionGroup solves is that you can both provide callbacks for the 3 transitions (appear, enter, leave) AND have your css classes applied. ReactCSSTransitionGroup does not allow for callbacks.

However, we've taken it one step farther to allow you to customize each individual child component rendered within the group. So that means you can provide props (such as animation duration, delay, etc) that apply to all children by setting them at the group level, OR you can override them by passing the props to the <Transition /> components that wrap your actual children.

Note: unlike ReactTransitionGroup and ReactCSSTransitionGroup all child components are required to be wrapped in <Transition>.

Lastly, we offer simpler prop names and a lot more customization:

• duration (duration, appearDuration, enterDuration, leaveDuration)
• delay (delay, appearDelay, enterDelay, leaveDelay)
• class names (the appear, enter, and leave props)
• a prefix (prepended to all classes)

Installation

yarn add animated-transition-group

Usage

import React from 'react'
import { connect } from 'react-redux'
import { TransitionGroup, Transition } from 'animated-transition-group'

const onLeave = () => console.log('left')
const onEmpty = () => console.log('group empty')

const PageSwitcher = ({ page }) =>
  <TransitionGroup 
    component='div'
    className='whatever'
    duration={300}
    delay={100}
    prefix='fade'
    onEmpty={onEmpty}
  >
    <Transition key={page} duration={500} enterDelay={500} leaveDelay={0} onLeave={onLeave}>
      {getComponent(page)}
    </Transition>

    // don't show link for the current page:
    <LinkRow>
      {page !== 'Home' && <Transition key={`${page}-link`>HOME<Transition>}
      {page !== 'List' && <Transition key={`${page}-link`>LIST<Transition>}
      {page !== 'Video' && <Transition key={`${page}-link`>VIDEO<Transition>}
    </LinkRow>
  </TransitionGroup>

const getComponent = page => {
  switch(page) {
    case 'Home':  
      return <Home />
    case 'List':  
      return <List />
    case 'Video':  
      return <Video />
  }
}

const mapState = ({ page }) => ({ page })
export default connect(mapState)(PageSwitcher)

note: you can have as many nested <Transition />'s as you want. This happens to be primarily for one child :)

The secret ingredient is obviously the key property passed to your children. That lets React differentiate between the components. More importantly it lets you define just a single component in this case, rather than require you to hack something together that has 2 components nested in the code at once. React just knows what to do.

The ReactTransitionGroup toolset hasn't received enough credit in my opinion--partly because the flaws our component here solves--but we believe the abstraction it provides to use state to determine when components should and should not be there (as you normally would), while keeping the concept of the actual duration embedded in the DOM separate, makes it world class. It allows you to render from state, just as you would hope...and without any hacked solutions or trickery.

As for having multiple nested Transition components, of course also use the key prop to uniquely identify them so React knows what to do, i.e. when to attach and detach them to/from the DOM.

API

The below props can be applied to both <TransitionGroup /> and <Transition />. The difference is that if you provide them to TransitionGroup, they will be passed down to Transition. And of course, if Transition supplies its own, it will override it. duh!

prefix: string

the string prepended to all classes like this: myPrefix-appear, myPrefix-appear-active, myPrefix-enter, etc

duration: number

the time in milliseconds that child components are expected to animate for

delay: number

the time in milliseconds that child components are supposed to wait before being animated. Instances won't be removed from the DOM until the sum of the delay and duration has been reached.

enterDuration: number

leaveDuration: number

appearDuration: number

by supplying these, you can customize the duration length (in ms) of the individual transition

enterDelay: number

leaveDelay: number

appearDelay: number

by supplying these, you can customize the delay length (in ms) of the individual transition

onAppear: Function

onEnter: Function

onLeave: Function

these callbacks will of course be called for the given transition

onBeforeAppear: Function

onBeforeEnter: Function

onBeforeLeave: Function

these callbacks will of course be called before their respective transition happens

appear: string

enter: string

leave: string

by suppling these you can override the classes applied, e.g: leave-active can be foobar-active. These are also very effective if you're using CSS Modules and don't want to define a global class with :global(.appear). Instead, do this:

import styles from '.styles'
<Transition appear={styles.appear} />

TransitionGroup only:

The following props are only available on <TransitionGroup />:

onFull: Function

called when the first Transition renders within TransitionGroup

onEmpty: Function

called when there are no nested <Transition /> components. It is called after the final component animates its departure, using the the duration and delay passed to TransitionGroup (not the child) to calculate that time.

zeroElements: number

to calculate whether there are zero nested children, sometimes you need to indicate what that number is. For example, if you have an array of children, when the array is empty, it's counted as 1 even though no children are rendered. So you set zeroElements={1}.