rv-window-scroller/dist/es/utils/onScroll.js

Window scroller component for react-virtualized and react-window

'no babel-plugin-flow-react-proptypes';

import { requestAnimationTimeout, cancelAnimationTimeout } from './requestAnimationTimeout';
/*:: import type WindowScroller from './WindowScroller.js';*/

var mountedInstances = [];
var originalBodyPointerEvents = null;
var disablePointerEventsTimeoutId = null;
var registeredScrollListeners = new WeakMap();

function enablePointerEventsIfDisabled() {
  if (disablePointerEventsTimeoutId) {
    disablePointerEventsTimeoutId = null;

    if (document.body && originalBodyPointerEvents != null) {
      document.body.style.pointerEvents = originalBodyPointerEvents;
    }

    originalBodyPointerEvents = null;
  }
}

function enablePointerEventsAfterDelayCallback() {
  enablePointerEventsIfDisabled();
  mountedInstances.forEach(function (instance) {
    return instance.__resetIsScrolling();
  });
}

function enablePointerEventsAfterDelay() {
  if (disablePointerEventsTimeoutId) {
    cancelAnimationTimeout(disablePointerEventsTimeoutId);
  }

  var maximumTimeout = 0;
  mountedInstances.forEach(function (instance) {
    maximumTimeout = Math.max(maximumTimeout, instance.props.scrollingResetTimeInterval);
  });
  disablePointerEventsTimeoutId = requestAnimationTimeout(enablePointerEventsAfterDelayCallback, maximumTimeout);
}

function onScrollWindow(event
/*: Event*/
) {
  if (event.currentTarget === window && originalBodyPointerEvents == null && document.body) {
    originalBodyPointerEvents = document.body.style.pointerEvents;
    document.body.style.pointerEvents = 'none';
  }

  enablePointerEventsAfterDelay();
  mountedInstances.forEach(function (instance) {
    if (instance.props.scrollElement === event.currentTarget) {
      instance.__handleWindowScrollEvent();
    }
  });
}

export function registerScrollListener(component
/*: WindowScroller*/
, element
/*: Element*/
) {
  if ( // !mountedInstances.some(instance => instance.props.scrollElement === element)
  !registeredScrollListeners.has(element)) {
    element.addEventListener('scroll', onScrollWindow);
    registeredScrollListeners.set(element, onScrollWindow);
  }

  mountedInstances.push(component);
}
export function unregisterScrollListener(component
/*: WindowScroller*/
, element
/*: Element*/
) {
  mountedInstances = mountedInstances.filter(function (instance) {
    return instance !== component;
  });

  if (!mountedInstances.length) {
    element.removeEventListener('scroll', onScrollWindow);
    element.removeEventListener('scroll', registeredScrollListeners.get(element));
    registeredScrollListeners["delete"](element);

    if (disablePointerEventsTimeoutId) {
      cancelAnimationTimeout(disablePointerEventsTimeoutId);
      enablePointerEventsIfDisabled();
    }
  }
}