code: function computeStripY() {
        if (this.hideVertical) {
          // 没有开启竖向滚动条
          return;
        }
        var clientEle = this.$refs['happy-scroll'];
        var slotEle = this.$slots.default[0]['elm'];
        // 竖向滚动条高度与元素高度百分比
        this.$refs.stripY.computeStrip(slotEle.scrollHeight, clientEle.clientHeight);
      }
docs: 计算横向滚动条高度与元素高度百分比