should be setInterval (this.float (), 10) this is wrong. There is no need for parentheses. Adding parentheses will only be executed once. And your code doesn't have to be written like this, the adFloat method is not necessary, just write it in mounted (). Timers can be defined in data.

data () {
  return {
    timer: null
  }
}
mounted () {
  this.$nextTick(function () {
    const self = this
    this.timer = setInterval(this.float, 10)
    this.$refs[].onmouseover = function () {
        clearInterval(self.timer)
    }
    this.$refs[].onmouseout = function () {
        self.timer = setInterval(self.float, 10)
    }
  })
}

try calling this.adFloat () in the mounted method. https://www.qqwenda.com