JS原生代码编写获取当前页面高度和触发滚动事件

//获取滚动条当前的位置
  function getScrollTop() {
    var scrollTop = 0;
    if (document.documentElement && document.documentElement.scrollTop) {
      scrollTop = document.documentElement.scrollTop;
    } else if (document.body) {
      scrollTop = document.body.scrollTop;
    }
    return scrollTop;
  }
  //获取当前可视范围的高度
  function getClientHeight() {
    var clientHeight = 0;
    if (document.body.clientHeight && document.documentElement.clientHeight) {
      clientHeight = Math.min(
        document.body.clientHeight,
        document.documentElement.clientHeight,
      );
    } else {
      clientHeight = Math.max(
        document.body.clientHeight,
        document.documentElement.clientHeight,
      );
    }
    return clientHeight;
  }
  //获取文档完整的高度
  function getScrollHeight() {
    return Math.max(
      document.body.scrollHeight,
      document.documentElement.scrollHeight,
    );
  }
  //滚动事件触发
  window.onscroll = function () {
    if (getScrollTop() + getClientHeight() == getScrollHeight()) {
      // 代码逻辑
    }
  };