funda-ui/lib/esm/Utils/plugins/bodyScrollLock.ts

React components using pure Bootstrap 5+ which does not contain any external style and script libraries.

// =================================================================
// based on https://github.com/willmcpo/body-scroll-lock
// =================================================================


// @flow
// Adopted and modified solution from Bohdan Didukh (2017)
// https://stackoverflow.com/questions/41594997/ios-10-safari-prevent-scrolling-behind-a-fixed-overlay-and-maintain-scroll-posi

interface BodyScrollOptions {
    reserveScrollBarGap?: boolean;
    allowTouchMove?: (el: any) => boolean;
}


interface Lock {
    targetElement: any;
    options: BodyScrollOptions;
}

// Older browsers don't support event options, feature detect it.
let hasPassiveEvents = false;
if (typeof window !== 'undefined') {
    const passiveTestOptions = {
        get passive() {
            hasPassiveEvents = true;
            return undefined;
        },
    };
    (window as any).addEventListener('testPassive', null, passiveTestOptions);
    (window as any).removeEventListener('testPassive', null, passiveTestOptions);
}

const isIosDevice =
    typeof window !== 'undefined' &&
    window.navigator &&
    window.navigator.platform &&
    (/iP(ad|hone|od)/.test(window.navigator.platform) ||
        (window.navigator.platform === 'MacIntel' && window.navigator.maxTouchPoints > 1));
type HandleScrollEvent = TouchEvent;

let locks: Array<Lock> = [];
let documentListenerAdded: boolean = false;
let initialClientY: number = -1;
let previousBodyOverflowSetting: any;
let previousBodyPosition: any;
let previousBodyPaddingRight: any;

// returns true if `el` should be allowed to receive touchmove events.
const allowTouchMove = (el: EventTarget): boolean =>
    locks.some(lock => {
        if (lock.options.allowTouchMove && lock.options.allowTouchMove(el)) {
            return true;
        }

        return false;
    });

const preventDefault = (rawEvent: HandleScrollEvent): boolean => {
    const e = rawEvent || window.event;

    // For the case whereby consumers adds a touchmove event listener to document.
    // Recall that we do document.addEventListener('touchmove', preventDefault, { passive: false })
    // in disableBodyScroll - so if we provide this opportunity to allowTouchMove, then
    // the touchmove event on document will break.
    if (allowTouchMove(e.target as any)) {
        return true;
    }

    // Do not prevent if the event has more than one touch (usually meaning this is a multi touch gesture like pinch to zoom).
    if (e.touches.length > 1) return true;

    if (e.preventDefault) e.preventDefault();

    return false;
};

const setOverflowHidden = (options?: BodyScrollOptions) => {
    // If previousBodyPaddingRight is already set, don't set it again.
    if (previousBodyPaddingRight === undefined) {
        const reserveScrollBarGap = !!options && options.reserveScrollBarGap === true;
        const scrollBarGap = window.innerWidth - document.documentElement.clientWidth;

        if (reserveScrollBarGap && scrollBarGap > 0) {
            const computedBodyPaddingRight = parseInt(window.getComputedStyle(document.body).getPropertyValue('padding-right'), 10);
            previousBodyPaddingRight = document.body.style.paddingRight;
            document.body.style.paddingRight = `${computedBodyPaddingRight + scrollBarGap}px`;
        }
    }

    // If previousBodyOverflowSetting is already set, don't set it again.
    if (previousBodyOverflowSetting === undefined) {
        previousBodyOverflowSetting = document.body.style.overflow;
        document.body.style.overflow = 'hidden';
    }
};

const restoreOverflowSetting = () => {
    if (previousBodyPaddingRight !== undefined) {
        document.body.style.paddingRight = previousBodyPaddingRight;

        // Restore previousBodyPaddingRight to undefined so setOverflowHidden knows it
        // can be set again.
        previousBodyPaddingRight = undefined;
    }

    if (previousBodyOverflowSetting !== undefined) {
        document.body.style.overflow = previousBodyOverflowSetting;

        // Restore previousBodyOverflowSetting to undefined
        // so setOverflowHidden knows it can be set again.
        previousBodyOverflowSetting = undefined;
    }
};

const setPositionFixed = () => window.requestAnimationFrame(() => {
    // If previousBodyPosition is already set, don't set it again.
    if (previousBodyPosition === undefined) {
        previousBodyPosition = {
            position: document.body.style.position,
            top: document.body.style.top,
            left: document.body.style.left
        };

        // Update the dom inside an animation frame
        const { scrollY, scrollX, innerHeight } = window;
        document.body.style.position = 'fixed';
        document.body.style.top = `${-scrollY}px`;
        document.body.style.left = `${-scrollX}px`;

        setTimeout(() => window.requestAnimationFrame(() => {
            // Attempt to check if the bottom bar appeared due to the position change
            const bottomBarHeight = innerHeight - window.innerHeight;
            if (bottomBarHeight && scrollY >= innerHeight) {
                // Move the content further up so that the bottom bar doesn't hide it
                document.body.style.top = `${-(scrollY + bottomBarHeight)}`;
            }
        }), 300)
    }
});

const restorePositionSetting = () => {
    if (previousBodyPosition !== undefined) {
        // Convert the position from "px" to Int
        const y = -parseInt(document.body.style.top, 10);
        const x = -parseInt(document.body.style.left, 10);

        // Restore styles
        document.body.style.position = previousBodyPosition.position;
        document.body.style.top = previousBodyPosition.top;
        document.body.style.left = previousBodyPosition.left;

        // Restore scroll
        window.scrollTo(x, y);

        previousBodyPosition = undefined;
    }
};

// https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollHeight#Problems_and_solutions
const isTargetElementTotallyScrolled = (targetElement: any): boolean =>
    targetElement ? targetElement.scrollHeight - targetElement.scrollTop <= targetElement.clientHeight : false;

const handleScroll = (event: HandleScrollEvent, targetElement: any): boolean => {
    const clientY = event.targetTouches[0].clientY - initialClientY;

    if (allowTouchMove(event.target as any)) {
        return false;
    }

    if (targetElement && targetElement.scrollTop === 0 && clientY > 0) {
        // element is at the top of its scroll.
        return preventDefault(event);
    }

    if (isTargetElementTotallyScrolled(targetElement) && clientY < 0) {
        // element is at the bottom of its scroll.
        return preventDefault(event);
    }

    event.stopPropagation();
    return true;
};

export const disableBodyScroll = (targetElement: any, options?: BodyScrollOptions): void => {
    // targetElement must be provided
    if (!targetElement) {
        // eslint-disable-next-line no-console
        console.error(
            'disableBodyScroll unsuccessful - targetElement must be provided when calling disableBodyScroll on IOS devices.'
        );
        return;
    }

    // disableBodyScroll must not have been called on this targetElement before
    if (locks.some(lock => lock.targetElement === targetElement)) {
        return;
    }

    const lock = {
        targetElement,
        options: options || {},
    };

    locks = [...locks, lock];

    if (isIosDevice) {
        setPositionFixed();
    } else {
        setOverflowHidden(options);
    }

    if (isIosDevice) {
        targetElement.ontouchstart = (event: HandleScrollEvent) => {
            if (event.targetTouches.length === 1) {
                // detect single touch.
                initialClientY = event.targetTouches[0].clientY;
            }
        };
        targetElement.ontouchmove = (event: HandleScrollEvent) => {
            if (event.targetTouches.length === 1) {
                // detect single touch.
                handleScroll(event, targetElement);
            }
        };

        if (!documentListenerAdded) {
            document.addEventListener('touchmove', preventDefault, hasPassiveEvents ? { passive: false } : undefined);
            documentListenerAdded = true;
        }
    }
};

export const clearAllBodyScrollLocks = (): void => {
    if (isIosDevice) {
        // Clear all locks ontouchstart/ontouchmove handlers, and the references.
        locks.forEach((lock: Lock) => {
            lock.targetElement.ontouchstart = null;
            lock.targetElement.ontouchmove = null;
        });

        if (documentListenerAdded) {
            (document as any).removeEventListener('touchmove', preventDefault, hasPassiveEvents ? { passive: false } : undefined);
            documentListenerAdded = false;
        }

        // Reset initial clientY.
        initialClientY = -1;
    }

    if (isIosDevice) {
        restorePositionSetting();
    } else {
        restoreOverflowSetting();
    }

    locks = [];
};

export const enableBodyScroll = (targetElement: any): void => {
    if (!targetElement) {
        // eslint-disable-next-line no-console
        console.error(
            'enableBodyScroll unsuccessful - targetElement must be provided when calling enableBodyScroll on IOS devices.'
        );
        return;
    }

    locks = locks.filter(lock => lock.targetElement !== targetElement);

    if (isIosDevice) {
        targetElement.ontouchstart = null;
        targetElement.ontouchmove = null;

        if (documentListenerAdded && locks.length === 0) {
            (document as any).removeEventListener('touchmove', preventDefault, hasPassiveEvents ? { passive: false } : undefined);
            documentListenerAdded = false;
        }
    }

    if (isIosDevice) {
        restorePositionSetting();
    } else {
        restoreOverflowSetting();
    }
};