| // @flow | |
| import { useState, useEffect } from 'react'; | |
| export const useAppScroller = () => { | |
| const [ref, setRef] = useState(null); | |
| useEffect(() => { | |
| if (!ref) setRef(document.getElementById('main')); | |
| }); | |
| const scrollToTop = () => { | |
| const elem = ref || document.getElementById('main'); | |
| if (elem) return (elem.scrollTop = 0); | |
| }; | |
| const scrollToBottom = () => { | |
| const elem = ref || document.getElementById('main'); | |
| if (elem) return (elem.scrollTop = elem.scrollHeight - elem.clientHeight); | |
| }; | |
| const scrollTo = (pos: number) => { | |
| const elem = ref || document.getElementById('main'); | |
| if (elem) return (elem.scrollTop = pos); | |
| }; | |
| return { scrollToTop, scrollTo, scrollToBottom, ref }; | |
| }; | |