Vue中better-scroll实现左右侧联动

```javascript
<script>
import BScroll from 'better-scroll'
export default {
  watch: {
    menus() {
      this.$nextTick(() => {        
        this._initRightLiTops()
this._initBScroll()
      })
    },
  },
  methods: {
    _initBScroll() {
      this.leftBScroll = new BScroll('.menu-left', {
        click: true,
        mouseWheel: true,
        probeType: 3,
      })
      this.rightBScroll = new BScroll('.menu-right', {
        click: true,
        mouseWheel: true,
        probeType: 3,
      })
      this.rightBScroll.on('scroll', (pos) => {
        var scrollY = Math.abs(pos.y)
        for (var i = 0; i < this.rightLiTops.length - 1; i++) {
          if (
            scrollY >= this.rightLiTops[i] &&
            scrollY < this.rightLiTops[i + 1]
          ) {