递归累加

changeTree(val) {
      var that = this
      let total = 0
      if (val.length !== 0) {
        val.forEach(item => {
          if (item.count) {
            total += item.count
          }
          if (item.bqList != null) {
            that.changeTree(item.bqList)
          }
        })
      }
      return total
},