diff --git a/ui/component/common/wait-until-on-page.jsx b/ui/component/common/wait-until-on-page.jsx index 53cb9886e..51d78ae8a 100644 --- a/ui/component/common/wait-until-on-page.jsx +++ b/ui/component/common/wait-until-on-page.jsx @@ -2,45 +2,73 @@ 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, skipWait?: boolean, placeholder?: any, + yOffset?: number, }; export default function WaitUntilOnPage(props: Props) { + const { yOffset } = props; const ref = React.useRef(); const [shouldRender, setShouldRender] = React.useState(false); - React.useEffect(() => { - const handleDisplayingRef = debounce((e) => { + const shouldElementRender = React.useCallback( + (ref) => { const element = ref && ref.current; if (element) { const bounding = element.getBoundingClientRect(); - if ( + // $FlowFixMe + const windowH = window.innerHeight || document.documentElement.clientHeight; + // $FlowFixMe + const windowW = window.innerWidth || document.documentElement.clientWidth; + + const isApproachingViewport = yOffset && bounding.top < windowH + yOffset; + const isInViewport = // also covers "element is larger than viewport". + 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) - ) { - setShouldRender(true); - } + bounding.top <= windowH && + bounding.left <= windowW; + + return isInViewport || isApproachingViewport; } - if (element && !shouldRender) { - window.addEventListener('scroll', handleDisplayingRef); - return () => window.removeEventListener('scroll', handleDisplayingRef); + return false; + }, + [yOffset] + ); + + // 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); + window.addEventListener('resize', handleDisplayingRef); + return () => { + window.removeEventListener('scroll', handleDisplayingRef); + window.removeEventListener('resize', handleDisplayingRef); + }; } - }, [ref, setShouldRender, shouldRender]); + }, [ref, setShouldRender, shouldRender, shouldElementRender]); const render = props.skipWait || shouldRender; diff --git a/ui/page/home/view.jsx b/ui/page/home/view.jsx index 0ccbf65d4..1941091a3 100644 --- a/ui/page/home/view.jsx +++ b/ui/page/home/view.jsx @@ -63,7 +63,7 @@ function HomePage(props: Props) { {index === 0 && <>{claimTiles}} {index !== 0 && ( - + {claimTiles} )}