Vue 返回缓存页 回到上次浏览位置

scrollBehavior (to, from,savedPosition) {
    if(savedPosition){
      return savedPosition
    }else {
      if(from.meta.keepAlive){
        from.meta.savedPosition = document.documentElement.scrollTop || document.body.scrollTop;
      }
      return {x: 0 , y: to.meta.savedPosition || 0}
    }
  },