overscroll/es/utils/dom/hasScrollBar.js

scroll

import { get } from '../css';
import { hasData } from './domData';

// 实际情况下 body documentElement 不会都设置 overflow: scroll
// 推荐 html, body { height: 100% } body { overflow: auto; }

function compose(funcA, funcB) {
  return function () {
    return funcA(funcB.apply(undefined, arguments));
  };
}

var scrollable = function scrollable(attr) {
  return function (dom) {
    return ['overlay', 'scroll', 'auto'].includes(get(dom, attr));
  };
};

export default (function (_ref) {
  var body = _ref.body,
      html = _ref.html,
      target = _ref.target,
      OVERSCROLLX = _ref.OVERSCROLLX,
      OVERSCROLLY = _ref.OVERSCROLLY;


  function hasScrollX(dom) {
    return dom.scrollWidth > dom.clientWidth && (hasData(dom, OVERSCROLLX) || scrollable('overflow-x')(dom));
  }

  function hasScrollY(dom) {
    return dom.scrollHeight > dom.clientHeight && (hasData(dom, OVERSCROLLY) || scrollable('overflow-y')(dom));
  }

  function scrollingElement() {
    var dom = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : target;

    return dom === body ? html : dom;
  }

  function hasScroll(dom) {
    return {
      x: hasScrollX(dom),
      y: hasScrollY(dom)
    };
  }

  return {
    hasScroll: compose(hasScroll, scrollingElement),
    hasScrollX: compose(hasScrollX, scrollingElement),
    hasScrollY: compose(hasScrollY, scrollingElement)
  };
});