Rocket.Chat/client/views/root/MainLayout/useViewportScrolling.ts

import { useEffect } from 'react';

export const useViewportScrolling = (): void => {
	useEffect(() => {
		document.documentElement.classList.remove('scroll');
		document.documentElement.classList.add('noscroll');

		return (): void => {
			document.documentElement.classList.add('scroll');
			document.documentElement.classList.remove('noscroll');
		};
	}, []);
};