Vue 的下拉刷新指令

    loadmore: {
      //自定义指令: 下拉加载
      bind(el, binding) {
        let p = 0;
        let t = 0;
        let down = true;
        el.addEventListener('scroll', function () {
          //判断是否向下滚动
          p = this.scrollTop;
          if (t < p) {
            down = true;
          } else {
            down = false;
          }
          t = p;
          //判断是否到底
          const sign = 10;
          const scrollDistance =
            this.scrollHeight - this.scrollTop - this.clientHeight;
          if (scrollDistance <= sign && down) {
            binding.value();
          }
        });
      },
    },