transitionable-routes

Perform transitions when changing routes with React Router

Install

npm i transitionable-routes

The Problem

The ability to add animations whenever a route changes seems like such a trivial feature but weirdly enough I haven't found a nice way of doing it with React and React Router.

All the examples I've seen out there – including the ones in the official docs – usually assume you are performing generic transitions such as fading in and out the routes entering and leaving. If you need more control over that, good luck.

At some point in time this was achievable via react-transition-group but at some point React Router had a major bump that broke integration with it and as a workaround the react-transition-group team changed the API in a way that for me was a downgrade since they've made much harder to make things customizable (they've added a in property that makes no sense to me and instead of controlling animations via callbacks you had to pass down how long transitions would take, which is an idea that I dislike very much).

Coming from a Flash background I remember this used to be a feature we took for granted. Either you rolled your own at the beginning of the project or you would have it available via frameworks (shout out to Potato (aka Patota) and Robotlegs).

The Solution

Keep in mind that this was put together in a few hours and is still experimental. If you have ideas on how to improve it, do chime in.

Out of desperation (I couldn't imagine this would take longer than a few minutes to ship) I decided to hack my way into a solution. I have started by writing the API that I wanted then started putting something together off of some good ideas that I've seen in the wild.

TransitionableSwitch

This is a simple stateful React component that acts as a replacement for React Router's Switch. It knows how to render route components based on the active route, but it also knows how to coordinate rendering of routes that are transitioning (either entering or leaving).

This component injects hooks to every route component that is transitioning so inside of it you have access to transition states.

The coordination of transition states is done via event emitters. These are responsible for communicating state from the switcher down to the component. I have tried using React ref for this but had a bad experience, specially when you're trying to wrap a Redux-connected component, so I went for good ol' event emitters (which still sounds kinda crazy but did the job well).

TransitionableComponent

This is a simple React component that automatically handles syncing the component to the event emitter and exposes all the hooks available for transitions:

• willAppear
• willEnter
• willLeave

All hooks receive a callback function as an argument so you can do whatever you want and call them once you're done.

Usage

import React from 'react'
import { render } from 'react-dom'
import { BrowserRouter, Route } from 'react-router-dom'
import { TransitionableSwitch, TransitionableComponent } from 'transitionable-routes'

const Home = () => <h1>Home</h1>

class About extends TransitionableComponent {
  constructor (props) {
    super(props)
    this.state = { transition: null }
  }

  willEnter (done) {
    this.setState({ transition: 'enter' }, done)
  }

  willLeave (done) {
    this.setState({ transition: 'leave' }, () => setTimeout(done, 500))
  }

  render () {
    const { transition } = this.state
    const style = {
      opacity: transition === 'enter' ? 1 : 0,
      transition: 'opacity 0.5s ease-out'
    }
    return <h1 style={style}>About</h1>
  }
}

class Contact extends TransitionableComponent {
  constructor (props) {
    super(props)
    this.state = { transition: null }
  }

  willEnter (done) {
    this.setState({ transition: 'enter' }, done)
  }

  willLeave (done) {
    this.setState({ transition: 'leave' }, () => setTimeout(done, 1000))
  }

  render () {
    const { transition } = this.state
    const style = {
      transform: `translateY(${transition === 'enter' ? 0 : '20px'})`,
      opacity: transition === 'enter' ? 1 : 0,
      transition: 'all 1s ease-out'
    }
    return <h1 style={style}>Contact</h1>
  }
}

const App = () => (
  <BrowserRouter>
    <TransitionableSwitch>
      <Route exact path='/' render={() => <Home />} />
      <Route path='/about' component={About} />
      <Route path='/contact' children={<Contact />} />
    </TransitionableSwitch>
  </BrowserRouter>
)

render(<App />, document.querySelector('[data-app]'))

Checkout the examples folder.

npm start

Conditional rendering

It's very common to want to conditionally render a route. Say you want to redirect logged out users to a sign in page instead of giving guest access to private routes:

import React from 'react'
import { Redirect, Route } from 'react-router-dom'
import SuperSecretRoute from './components/SuperSecretRoute'

const withAuth = (props, Component) => {
  // If user is logged in, we're good to go, just return the component itself
  if (isUserLoggedIn) return <Component {...props} />

  // It's very handy to have "referrer" when you're redirecting, so we use local state for that
  const referrer = props.path || props.location.pathname

  // Return a `Redirect` component pointing to a sign in page
  return (
    <Redirect
      to={{
        pathname: '/sign-in',
        state: { referrer },
      }}
    />
  );
};

const App = () => (
  <TransitionableSwitch>
    <Route path="/super-secret-route" render={props => withAuth(props, SuperSecretRoute)} />
  </TransitionableSwitch>
);

Project Pipeline

API

Even though we have TransitionableComponent it still feels like we could improve the API since there's quite a lot of boilerplate involved as it is right now. To create a route component that is able to perform transitions:

1. Create a new React component that extends TransitionableComponent
2. Override transition lifecycle methods and fire done()
3. If your component needs to do anything on either componentWillMount() or componentWillUnmount() you have to remember to invoke super() otherwise things will break
4. Whenever implementing a transition you must make your component stateful and manually change transition steps so you can do your thing on render(), this can become annoying if you have a lot of custom transitions

As mentioned on #1 this could perhaps be improved with HOCs instead of using a class like TransitionableComponent but I'm not sure yet on what's the best thing to do there.

Examples

Current examples are super simple and limited. It would be nice to have better ones that properly showcase this project's capabilities.

Related

• animate
• react-router-v4-transition

License

MIT © Rafael Rinaldi

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