Hey you! Yea you! Do you need a quick and simple fade animation on your React component? Don't feel like installing a library?
Then let's go! 💨💨💨

Show me the code already! 👀

The hook returns [isVisible, setVisible, fadeProps], just like useState() hook, but you also need to set the fadeProps on the element you want to fade.

const MyFadingComponent = () => {
    // Just like useState() hook, the fadeProps go on the fading DOM element
    const [isVisible, setVisible, fadeProps] = useFade();

    // You can use isVisible to mount/unmount the component!
    return <>
        <button onClick={() => setVisible(!isVisible)}>Toggle visibility</button>
        {isVisible && <h2 {...fadeProps}>Now you see me...</h2>}
    </>;
};

And the hook! 🎣

It uses onAnimationEnd to delay setting the isVisible state to false, which allows the animation to finish before the component unmounts!

const useFade = (initial) => {
    const [show, setShow] = useState(initial);
    const [isVisible, setVisible] = useState(show);

    // Update visibility when show changes
    useEffect(() => {
        if (show) setVisible(true);
    }, [show]);

    // When the animation finishes, set visibility to false
    const onAnimationEnd = () => {
        if (!show) setVisible(false);
    };

    const style = { animation: `${show ? "fadeIn" : "fadeOut"} .3s` };

    // These props go on the fading DOM element
    const fadeProps = {
        style,
        onAnimationEnd
    };

    return [isVisible, setShow, fadeProps];
};

Styles 💅

@keyframes fadeIn {
    0% { opacity: 0; }
    100% { opacity: 1; }
}

@keyframes fadeOut {
    0% { opacity: 1; }
    100% { opacity: 0; }
}

What's the point? 🙄

If we would use the useState() hook and then apply the state with an expression like isVisible && <Component />, our component will unmount before the CSS animation has finished, which is not what we want! The useFade() hook delays unmounting until the animation is finished.

What's cool about this? 😎

The syntax is just like useState(), you can simply use an isVisible && <Component /> expression to mount/unmount the component.

Here's how you do it with React Transition Group, you need a wrapper component and wire the enter/exit animation to the state yourself, yuck! Framer Motion and React Spring are similar.

Room for improvement (please help!)

Toggling between two elements does not really work at the moment:

const [isVisible, setVisible, fromProps, toProps] = useFade();

{isVisible ? <ComponentA {...fromProps} /> : <ComponentB {...toProps} />}

I'm trying to pass the opposite fade animation to ComponentB, but can't figure out how to get it right. If you have an idea, let me know!