beforeRouteLeave (to, from, next) {
    if (to.name === 'pageA') {   /* pageA是需要跳转的路由   */
      // console.log('返回管理页面')
      if (this.$vnode && this.$vnode.data.keepAlive) {
        if (this.$vnode.parent && this.$vnode.parent.componentInstance && this.$vnode.parent.componentInstance.cache) {
          if (this.$vnode.componentOptions) {
            var key = this.$vnode.key == null
              ? this.$vnode.componentOptions.Ctor.cid + (this.$vnode.componentOptions.tag ? `::${this.$vnode.componentOptions.tag}` : '')
              : this.$vnode.key
            var cache = this.$vnode.parent.componentInstance.cache
            var keys = this.$vnode.parent.componentInstance.keys
            if (cache[key]) {
              if (keys.length) {
                var index = keys.indexOf(key)
                if (index > -1) {
                  keys.splice(index, 1)
                }
              }
              delete cache[key]
            }
          }
        }
      }
      this.$destroy()
    }
    next()
  },