清理interval

    Marquee2 () {
      let ul = document.getElementById(‘ul‘)
      let ul1 = document.getElementById(‘ul1‘)
      // let ul2 = document.getElementById(‘ul2‘)
      if (!(ul1 && ul)) {
        return
      }
      if (ul.scrollTop >= ul1.offsetHeight) {
        ul.scrollTop = 0
      } else {
        ul.scrollTop++
      }
    },

  destroyed () {
    // 清掉intervel
    clearInterval(this.marqueeTimer)
  },