endlessflow/dist/components/InfiniteScroll.js

A lightweight and customizable infinite scroll library

"use strict";

function _typeof(o) { "@babel/helpers - typeof"; return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (o) { return typeof o; } : function (o) { return o && "function" == typeof Symbol && o.constructor === Symbol && o !== Symbol.prototype ? "symbol" : typeof o; }, _typeof(o); }
Object.defineProperty(exports, "__esModule", {
  value: true
});
exports["default"] = InfiniteScroll;
var React = _interopRequireWildcard(require("react"));
function _getRequireWildcardCache(e) { if ("function" != typeof WeakMap) return null; var r = new WeakMap(), t = new WeakMap(); return (_getRequireWildcardCache = function _getRequireWildcardCache(e) { return e ? t : r; })(e); }
function _interopRequireWildcard(e, r) { if (!r && e && e.__esModule) return e; if (null === e || "object" != _typeof(e) && "function" != typeof e) return { "default": e }; var t = _getRequireWildcardCache(r); if (t && t.has(e)) return t.get(e); var n = { __proto__: null }, a = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var u in e) if ("default" !== u && {}.hasOwnProperty.call(e, u)) { var i = a ? Object.getOwnPropertyDescriptor(e, u) : null; i && (i.get || i.set) ? Object.defineProperty(n, u, i) : n[u] = e[u]; } return n["default"] = e, t && t.set(e, n), n; }
function InfiniteScroll(_ref) {
  var isLoading = _ref.isLoading,
    hasMore = _ref.hasMore,
    next = _ref.next,
    _ref$threshold = _ref.threshold,
    threshold = _ref$threshold === void 0 ? 1 : _ref$threshold,
    _ref$root = _ref.root,
    root = _ref$root === void 0 ? null : _ref$root,
    _ref$rootMargin = _ref.rootMargin,
    rootMargin = _ref$rootMargin === void 0 ? "0px" : _ref$rootMargin,
    reverse = _ref.reverse,
    children = _ref.children;
  var observer = React.useRef();
  // This callback ref will be called when it is dispatched to an element or detached from an element,
  // or when the callback function changes.
  var observerRef = React.useCallback(function (element) {
    var safeThreshold = threshold;
    if (threshold < 0 || threshold > 1) {
      console.warn("threshold should be between 0 and 1. You are exceed the range. will use default value: 1");
      safeThreshold = 1;
    }
    // When isLoading is true, this callback will do nothing.
    // It means that the next function will never be called.
    // It is safe because the intersection observer has disconnected the previous element.
    if (isLoading) return;
    if (observer.current) observer.current.disconnect();
    if (!element) return;

    // Create a new IntersectionObserver instance because hasMore or next may be changed.
    observer.current = new IntersectionObserver(function (entries) {
      if (entries[0].isIntersecting && hasMore) {
        next();
      }
    }, {
      threshold: safeThreshold,
      root: root,
      rootMargin: rootMargin
    });
    observer.current.observe(element);
  }, [hasMore, isLoading, next, threshold, root, rootMargin]);
  var flattenChildren = React.useMemo(function () {
    return React.Children.toArray(children);
  }, [children]);
  return /*#__PURE__*/React.createElement(React.Fragment, null, flattenChildren.map(function (child, index) {
    if (! /*#__PURE__*/React.isValidElement(child)) {
      process.env.NODE_ENV === "development" && console.warn("You should use a valid element with InfiniteScroll");
      return child;
    }
    var isObserveTarget = reverse ? index === 0 : index === flattenChildren.length - 1;
    var ref = isObserveTarget ? observerRef : null;
    return /*#__PURE__*/React.cloneElement(child, {
      ref: ref
    });
  }));
}