diff --git a/ui/component/common/wait-until-on-page.jsx b/ui/component/common/wait-until-on-page.jsx index 53cb9886e..5d2bb734f 100644 --- a/ui/component/common/wait-until-on-page.jsx +++ b/ui/component/common/wait-until-on-page.jsx @@ -2,7 +2,7 @@ import React from 'react'; import debounce from 'util/debounce'; -const DEBOUNCE_SCROLL_HANDLER_MS = 25; +const DEBOUNCE_SCROLL_HANDLER_MS = 50; type Props = { children: any, @@ -14,33 +14,48 @@ export default function WaitUntilOnPage(props: Props) { const ref = React.useRef(); const [shouldRender, setShouldRender] = React.useState(false); - React.useEffect(() => { - const handleDisplayingRef = debounce((e) => { - const element = ref && ref.current; - if (element) { - const bounding = element.getBoundingClientRect(); - if ( - bounding.bottom >= 0 && - bounding.right >= 0 && - // $FlowFixMe - bounding.top <= (window.innerHeight || document.documentElement.clientHeight) && - // $FlowFixMe - bounding.left <= (window.innerWidth || document.documentElement.clientWidth) - ) { - setShouldRender(true); - } + const shouldElementRender = React.useCallback((ref) => { + const element = ref && ref.current; + if (element) { + const bounding = element.getBoundingClientRect(); + if ( + bounding.width > 0 && + bounding.height > 0 && + bounding.bottom >= 0 && + bounding.right >= 0 && + // $FlowFixMe + bounding.top <= (window.innerHeight || document.documentElement.clientHeight) && + // $FlowFixMe + bounding.left <= (window.innerWidth || document.documentElement.clientWidth) + ) { + return true; } + } + return false; + }, []); - if (element && !shouldRender) { - window.addEventListener('scroll', handleDisplayingRef); - return () => window.removeEventListener('scroll', handleDisplayingRef); + // Handles "element is already in viewport when mounted". + React.useEffect(() => { + setTimeout(() => { + if (!shouldRender && shouldElementRender(ref)) { + setShouldRender(true); + } + }, 500); + }, []); // eslint-disable-line react-hooks/exhaustive-deps + + // Handles "element scrolled into viewport". + React.useEffect(() => { + const handleDisplayingRef = debounce(() => { + if (shouldElementRender(ref)) { + setShouldRender(true); } }, DEBOUNCE_SCROLL_HANDLER_MS); - if (ref) { - handleDisplayingRef(); + if (ref && ref.current && !shouldRender) { + window.addEventListener('scroll', handleDisplayingRef); + return () => window.removeEventListener('scroll', handleDisplayingRef); } - }, [ref, setShouldRender, shouldRender]); + }, [ref, setShouldRender, shouldRender, shouldElementRender]); const render = props.skipWait || shouldRender;