React animate transition between components

Question

I'd like to animate between two components where the first component fades out and is removed from the DOM before the next component is added to the DOM and fades in. Otherwise, the new component is added to the DOM and takes up space before the old component is removed. You can see the problem in this fiddle:

http://jsfiddle.net/phepyezx/4

// css snippet
.switch-enter {
    opacity: 0.01;
}
.switch-enter.switch-enter-active {
    opacity: 1.0;
}
.switch-leave {
    opacity: 1.0;
}
.switch-leave.switch-leave-active {
    opacity: 0;
}

// React snippet 
<ReactCSSTransitionGroup transitionName="switch">
    <div key={key} className={className}>{this.text()}</div>
</ReactCSSTransitionGroup>

An unacceptable solution (for me) is to hide the original component with css before transitioning to the new component as seen here:

http://jsfiddle.net/phepyezx/5

// Change to css
.switch-leave {
    visibility: hidden;
    height: 0px;
    width: 0px;
    opacity: 1.0;
}

Is there a way to "delay" react from mounting a new component before the original is removed? I'm open to velocity or some other library to achieve this.

Thanks

Answer 1

Another solution is to make the incoming and outgoing elements take up the same space, for example by having them both absolutely positioned:

<ReactCSSTransitionGroup
    className="container"
    component="div"
    transitionName="switch">
...

.container {
    position: relative;
}
.container > div {
    position: absolute;
}

http://jsfiddle.net/phepyezx/7/

---

You can use transition-delay to wait until the leaving component disappears before making the entering component appear, e.g.:

.fade-enter {
  opacity: 0.01;
}
.fade-enter.fade-enter-active {
  opacity: 1;
  transition: opacity 1s;
  transition-delay: 1s;
}

.fade-leave {
  opacity: 1;
}
.fade-leave.fade-leave-active {
  opacity: 0.01;
  transition: opacity 1s;
}

Answer 2

Solved using the componentWillUnmount() lifecycle method.

http://jsfiddle.net/phepyezx/9/

Here's the code:

var ReactCSSTransitionGroup = React.addons.CSSTransitionGroup;

const Off = React.createClass({
    componentWillUnmount () {
        this.props.handleTransitionEnd();
    },
    render()  {
        return (
            <div className="off button">OFF</div>
        )
    }
});

const On = React.createClass({
    componentWillUnmount () {
        this.props.handleTransitionEnd();
    },
    render()  {
        return (
            <div className="on button">ON</div>
        )
    }
});

var Switch = React.createClass({
    getInitialState: function() {
        return {
            on: false,
            transitionEnd: true
        };
    },

    toggle: function(e) {
        this.setState({
            on: !this.state.on,
            transitionEnd: false
        });
    },

    handleTransitionEnd() {
        this.setState({transitionEnd: true});
    },

    renderOff() {
        if (! this.state.on && this.state.transitionEnd) {
            return (
                <Off key="off" handleTransitionEnd={this.handleTransitionEnd} />
            )
        }
    },

    renderOn() {
        if (this.state.on && this.state.transitionEnd) {
            return (
                <On key="on" handleTransitionEnd={this.handleTransitionEnd} />
            )
        }
    },

    render: function() {
        return (
            <div>
              <button onClick={this.toggle}>Toggle</button>
              <ReactCSSTransitionGroup transitionName="switch">
                {this.renderOff()}
                {this.renderOn()}
              </ReactCSSTransitionGroup>
            </div>
        );         
    }
});

React.render(<Switch/>, document.getElementById("switch"));

And the relevant css:

.switch-enter {
    opacity: 0.01;
}
.switch-enter.switch-enter-active {
    opacity: 1.0;
    transition: opacity 500ms ease-in;
}
.switch-leave {
    opacity: 1.0;
}
.switch-leave.switch-leave-active {
    opacity: 0;
    transition: opacity 500ms ease-out;
}

You can achieve the same effective result with Jonny Buchanan's answer which uses absolute positioning and a delay instead of componentWillUnmount()

Answer 3

If you want to delay the rendering of the next component, you could use something like this:

import React, { Component } from 'react';

export default class DelayedRender extends Component {

    static propTypes = {
        delay: React.PropTypes.number.isRequired,
        children: React.PropTypes.element,
        className: React.PropTypes.string
    };

    constructor(props) {
        super(props);

        this.state = {
            render: false
        };
    }

    componentDidMount() {
        setTimeout(() => {
            const delayedClassNames = this.refs.noDelayed.className;
            this.setState({
                render: true,
                classNames: delayedClassNames
            });
        }, this.props.delay);
    }

    render() {
        const { children, className } = this.props;
        return this.state.render ?
            <div className={this.state.classNames}>{children}</div> :
            <div className={className} ref="noDelayed" ></div>;
    }
}

And in your render method:

const ROUTE_TRANSITION_TIME = 500;
const views = [];

if (shouldRenderDelayedRoute) {
    views.push(
        <DelayedRender delay={ROUTE_TRANSITION_TIME} key="book">
            <A ref="book"/>
        </DelayedRender>
    );
} else {
    views.push(<B key="library"/>);
} 

<ReactCSSTransitionGroup
   transitionEnterTimeout={ROUTE_TRANSITION_TIME}
   transitionLeaveTimeout={ROUTE_TRANSITION_TIME}
   transitionName="fade-transition"
                        >
    {views}
</ReactCSSTransitionGroup>