TelegramPWA/src/util/scrollLock.ts

80 lines
2.5 KiB
TypeScript

let scrollLockEl: HTMLElement | null | undefined;
let excludedClosestSelector: string | undefined;
const IGNORED_KEYS: Record<string, boolean> = {
Down: true,
ArrowDown: true,
Up: true,
ArrowUp: true,
Left: true,
ArrowLeft: true,
Right: true,
ArrowRight: true,
' ': true,
PageUp: true,
PageDown: true,
End: true,
Home: true,
Tab: true,
};
function isTextBox(target: EventTarget | null) {
if (!target || !(target instanceof HTMLElement)) return false;
const element = target;
const tagName = element.tagName.toLowerCase();
if (tagName === 'textarea') return true;
if (tagName !== 'input') return false;
const type = element.getAttribute('type');
if (!type) return false;
const inputTypes = [
'text', 'password', 'number', 'email', 'tel', 'url',
'search', 'date', 'datetime', 'datetime-local', 'time', 'month', 'week',
];
return inputTypes.indexOf(type.toLowerCase()) > -1;
}
export const getTouchY = (e: WheelEvent | TouchEvent | React.WheelEvent | React.TouchEvent) => {
return ('changedTouches' in e ? e.changedTouches[0].clientY : 0);
};
const preventDefault = (e: WheelEvent | TouchEvent) => {
const deltaY = 'deltaY' in e ? e.deltaY : getTouchY(e);
if (
!scrollLockEl
// Allow overlay scrolling
|| !scrollLockEl.contains(e.target as HTMLElement)
// Prevent top overscroll
|| (scrollLockEl.scrollTop <= 0 && deltaY <= 0)
// Prevent bottom overscroll
|| (scrollLockEl.scrollTop >= (scrollLockEl.scrollHeight - scrollLockEl.offsetHeight) && deltaY >= 0)
) {
if (excludedClosestSelector && (e.target as HTMLElement).closest(excludedClosestSelector)) return;
e.preventDefault();
}
};
function preventDefaultForScrollKeys(e: KeyboardEvent) {
if (IGNORED_KEYS[e.key] && !isTextBox(e.target)) {
e.preventDefault();
}
}
export function disableScrolling(el?: HTMLElement | null, _excludedClosestSelector?: string) {
scrollLockEl = el;
excludedClosestSelector = _excludedClosestSelector;
// Disable scrolling in Chrome
document.addEventListener('wheel', preventDefault, { passive: false });
document.addEventListener('touchmove', preventDefault, { passive: false });
document.onkeydown = preventDefaultForScrollKeys;
}
export function enableScrolling() {
scrollLockEl = undefined;
excludedClosestSelector = undefined;
document.removeEventListener('wheel', preventDefault); // Enable scrolling in Chrome
document.removeEventListener('touchmove', preventDefault);
// eslint-disable-next-line no-null/no-null
document.onkeydown = null;
}