function getScrollTop() {
  var scrollTop = 0;
  var bodyScrollTop = 0;
  var documentScrollTop = 0;

  if (document.body) {
    bodyScrollTop = document.body.scrollTop;
  }

  if (document.documentElement) {
    documentScrollTop = document.documentElement.scrollTop;
  }

  scrollTop = bodyScrollTop - documentScrollTop > 0 ? bodyScrollTop : documentScrollTop;
  return scrollTop;
} // 文档的总高度


function getScrollHeight() {
  var scrollHeight = 0;
  var bodyScrollHeight = 0;
  var documentScrollHeight = 0;

  if (document.body) {
    bodyScrollHeight = document.body.scrollHeight;
  }

  if (document.documentElement) {
    documentScrollHeight = document.documentElement.scrollHeight;
  }

  scrollHeight = bodyScrollHeight - documentScrollHeight > 0 ? bodyScrollHeight : documentScrollHeight;
  return scrollHeight;
} // 浏览器视口的高度


function getWindowHeight() {
  var windowHeight = 0;

  if (document.compatMode === 'CSS1Compat') {
    windowHeight = document.documentElement.clientHeight;
  } else {
    windowHeight = document.body.clientHeight;
  }

  return windowHeight;
}

export function isReachBottom(offset) {
  if (offset === void 0) {
    offset = 0;
  }

  return getScrollTop() + getWindowHeight() + offset >= getScrollHeight();
}