在点击上一章和下一章节的时候， 滚动条在走，但是updated的函数没有触发

  methods: {
    onProgressChange (progress) {
      this.setProgress(progress).then(() => {
        this.displayProgress()
        this.updateProgressBg()
      })
    },
    onProgressInput (progress) {
      this.setProgress(progress).then(() => {
        this.displayProgress()
        this.updateProgressBg()
      })
    },
    displayProgress () {
      const cfi = this.currentBook.locations.cfiFromPercentage(this.progress / 100)
      this.display(cfi)
    },
    prevSection () {
      if (this.section > 0 && this.bookAvailable) {
        this.setSection(this.section - 1).then(() => {
          this.displaySection()
        })
      }
    },
    nextSection () {
      if (this.section < this.currentBook.spine.length - 1 && this.bookAvailable) {
        this.setSection(this.section + 1).then(() => {
          this.displaySection()
        })
      }
    },
    displaySection () {
      const sectionInfo = this.currentBook.section(this.section)
      if (sectionInfo && sectionInfo.href) {
        this.display(sectionInfo.href)
      }
    },
    // 更新进度条
    updateProgressBg () {
      this.$refs.refProgress.style.backgroundSize = `${this.progress}% 100%`
    }
  },
  // 这里点击进度条菜单没有触发滚动条更新，我这里用了父子传参来触发这个滚动条更新，
  props: {
    currentIndex: Number
  },
  watch: {
    currentIndex (newval, oldval) {
      if (newval === 2) this.updateProgressBg()
    }
  },
  updated () {
    this.updateProgressBg()
  }

// 刷新当前进度条位置
refreshLocation () {
  // 获取电子书当前定位
  const currentLocation = this.currentBook.rendition.currentLocation()
  if (!currentLocation.start) return
  const startCfi = currentLocation.start.cfi
  const progress = this.currentBook.locations.percentageFromCfi(currentLocation.start.cfi)
  this.setProgress(Math.floor(progress * 100))
  if (currentLocation.start) {
    this.setSection(currentLocation.start.index)
  }
  saveLocation(this.fileName, startCfi)
},
display (target, cb) {
  if (target) {
    this.currentBook.rendition.display(target).then(() => {
      this.refreshLocation()
      if (cb) cb()
    })
  } else {
    this.currentBook.rendition.display().then(() => {
      this.refreshLocation()
      if (cb) cb()
    })
  }
}

然而这里点击上一章和点击下一张的时候，这个this.updateProgressBg() 依然没有触发， 实在是不明白，这个updated函数在这里的意义。其实按道理说，应该会触发这个updated函数的啊，