InternshipProject/node_modules/rc-virtual-list/es/hooks/useOriginScroll.js

import { useRef } from 'react';
export default (function (isScrollAtTop, isScrollAtBottom) {
  // Do lock for a wheel when scrolling
  var lockRef = useRef(false);
  var lockTimeoutRef = useRef(null);

  function lockScroll() {
    clearTimeout(lockTimeoutRef.current);
    lockRef.current = true;
    lockTimeoutRef.current = setTimeout(function () {
      lockRef.current = false;
    }, 50);
  } // Pass to ref since global add is in closure


  var scrollPingRef = useRef({
    top: isScrollAtTop,
    bottom: isScrollAtBottom
  });
  scrollPingRef.current.top = isScrollAtTop;
  scrollPingRef.current.bottom = isScrollAtBottom;
  return function (deltaY) {
    var smoothOffset = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : false;
    var originScroll = // Pass origin wheel when on the top
    deltaY < 0 && scrollPingRef.current.top || // Pass origin wheel when on the bottom
    deltaY > 0 && scrollPingRef.current.bottom;

    if (smoothOffset && originScroll) {
      // No need lock anymore when it's smooth offset from touchMove interval
      clearTimeout(lockTimeoutRef.current);
      lockRef.current = false;
    } else if (!originScroll || lockRef.current) {
      lockScroll();
    }

    return !lockRef.current && originScroll;
  };
});