vue监听滚动条事件

代码

...省略...
  mounted() {
    // 监听页面滚动事件
    window.addEventListener("scroll", this.scrolling);

  },
methods: {
scrolling() {
      // 滚动条距文档顶部的距离
      let scrollTop =
        window.pageYOffset ||
        document.documentElement.scrollTop ||
        document.body.scrollTop;
      // 滚动条滚动的距离
      let scrollStep = scrollTop - this.oldScrollTop;
      console.log("header 滚动距离 ", scrollTop);
      // 更新——滚动前，滚动条距文档顶部的距离
      this.oldScrollTop = scrollTop;

      //变量windowHeight是可视区的高度
      let windowHeight =
        document.documentElement.clientHeight || document.body.clientHeight;
      //变量scrollHeight是滚动条的总高度
      let scrollHeight =
        document.documentElement.scrollHeight || document.body.scrollHeight;

      //滚动条到底部的条件
      if (scrollTop + windowHeight == scrollHeight) {
        //你想做的事情
        console.log("header  你已经到底部了");
      }
      if (scrollStep < 0) {
        console.log("header 滚动条向上滚动了！");
      } else {
        console.log("header  滚动条向下滚动了！");
      }
      // 判断是否到了最顶部
      if (scrollTop <= 0) {
        console.log("header 到了最顶部")
      } 
    },

},
  beforeDestroy() {
    window.removeEventListener("scroll", this.scrolling);
  },
  ...省略 ...

效果