7775eb9641
By using `overflow-y` instead of `overflow` using `endsWith` can be avoided and represents the data we are actually interested in here more accurately.
86 lines
2.7 KiB
TypeScript
86 lines
2.7 KiB
TypeScript
type ScrollBehavior = 'auto' | 'smooth' | 'instant';
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export function getScrollContainer(el: HTMLElement | null): HTMLElement | null {
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if (el == null || el.tagName === 'HTML') return null;
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const overflow = window.getComputedStyle(el).getPropertyValue('overflow-y');
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if (overflow === 'scroll' || overflow === 'auto') {
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return el;
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} else {
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return getScrollContainer(el.parentElement);
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}
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}
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export function getScrollPosition(el: Element | null): number {
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const container = getScrollContainer(el);
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return container == null ? window.scrollY : container.scrollTop;
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}
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export function isTopVisible(el: Element | null): boolean {
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const scrollTop = getScrollPosition(el);
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const topPosition = el.offsetTop; // TODO: container内でのelの相対位置を取得できればより正確になる
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return scrollTop <= topPosition;
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}
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export function isBottomVisible(el: HTMLElement, tolerance = 1, container = getScrollContainer(el)) {
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if (container) return el.scrollHeight <= container.clientHeight + Math.abs(container.scrollTop) + tolerance;
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return el.scrollHeight <= window.innerHeight + window.scrollY + tolerance;
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}
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export function onScrollTop(el: Element, cb) {
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const container = getScrollContainer(el) || window;
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const onScroll = ev => {
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if (!document.body.contains(el)) return;
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if (isTopVisible(el)) {
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cb();
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container.removeEventListener('scroll', onScroll);
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}
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};
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container.addEventListener('scroll', onScroll, { passive: true });
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}
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export function onScrollBottom(el: Element, cb) {
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const container = getScrollContainer(el) || window;
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const onScroll = ev => {
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if (!document.body.contains(el)) return;
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const pos = getScrollPosition(el);
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if (pos + el.clientHeight > el.scrollHeight - 1) {
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cb();
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container.removeEventListener('scroll', onScroll);
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}
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};
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container.addEventListener('scroll', onScroll, { passive: true });
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}
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export function scroll(el: Element, options: {
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top?: number;
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left?: number;
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behavior?: ScrollBehavior;
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}) {
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const container = getScrollContainer(el);
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if (container == null) {
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window.scroll(options);
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} else {
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container.scroll(options);
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}
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}
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export function scrollToTop(el: Element, options: { behavior?: ScrollBehavior; } = {}) {
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scroll(el, { top: 0, ...options });
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}
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export function scrollToBottom(el: Element, options: { behavior?: ScrollBehavior; } = {}) {
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scroll(el, { top: 99999, ...options }); // TODO: ちゃんと計算する
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}
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export function isBottom(el: Element, asobi = 0) {
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const container = getScrollContainer(el);
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const current = container
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? el.scrollTop + el.offsetHeight
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: window.scrollY + window.innerHeight;
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const max = container
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? el.scrollHeight
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: document.body.offsetHeight;
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return current >= (max - asobi);
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}
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