This content originally appeared on DEV Community and was authored by Thomas Ledoux
While developing my personal website, I noticed that my mobile menu appeared for a split second and then moved out of the screen.
My mobile menu is placed on the right side of the screen by using the following CSS:
.navigation {
transform: translateX(100%)
}
To make the menu come into the screen smoothly, I used the following CSS:
.navigation {
transition-property: transform;
transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
transition-duration: 150ms;
}
By adding this transition in my initial CSS, the menu will be transformed to the right side of the screen but with a duration of 150ms, so this will be clearly visible when the page loads.
To avoid this behaviour, I had to find a way to only apply the transition once the React app is already mounted.
For this use case, I found a custom useIsMounted hook useful.
import { useRef, useEffect } from 'react';
const useIsMounted = () => {
const isMounted = useRef(false);
useEffect(() => {
isMounted.current = true;
return () => isMounted.current = false;
}, []);
return isMounted;
};
export default useIsMounted;
Then in my component, I can easily import this hook and use it:
const Navigation = () => {
const isMounted = useIsMounted();
return (<div className={`navigation ${isMounted ? 'mounted' : ''}`}></div>)
}
My CSS then becomes this:
.navigation.mounted {
transition-property: transform;
transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
transition-duration: 150ms;
}
And that's it! No more unwanted animations on page load.
This will also help to increase your Cumulative Layout Shift (https://web.dev/cls) if you were encountering the same thing as I was, because your layout will not shift anymore, so it's a win-win!
You can see the end result here: https://thomasledoux.be (I use Tailwind on my site, so the example code is not exactly the same).
This content originally appeared on DEV Community and was authored by Thomas Ledoux
Thomas Ledoux | Sciencx (2021-04-29T17:46:53+00:00) Avoiding flash of unwanted animation on first render in React. Retrieved from https://www.scien.cx/2021/04/29/avoiding-flash-of-unwanted-animation-on-first-render-in-react/
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