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blockScroll.ts
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blockScroll.ts
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interface IElementOverflow {
count: number;
value: string;
}
const elementsOverflows = new Map<HTMLElement, IElementOverflow>();
function blockElement(element: HTMLElement) {
const overflow = elementsOverflows.get(element);
if (overflow) {
overflow.count++;
} else {
elementsOverflows.set(element, {
count: 1,
value: element.style.overflow
});
element.style.overflow = 'hidden';
}
}
function unblockElement(element: HTMLElement) {
const overflow = elementsOverflows.get(element);
if (!overflow) {
return;
}
overflow.count--;
if (!overflow.count) {
element.style.overflow = overflow.value;
elementsOverflows.delete(element);
}
}
/**
* Block scroll.
* @param element - HTML-element to block scroll.
* @return Unblock scroll.
*/
export function blockScroll(element = document.body) {
const {
documentElement
} = document;
let currentElement = element;
let restore: HTMLElement[] = [];
do {
restore.push(currentElement);
blockElement(currentElement);
currentElement = currentElement.parentElement;
} while (currentElement !== documentElement);
currentElement = null;
return () => {
if (restore === null) {
return;
}
restore.forEach(unblockElement);
restore = null;
};
}