数据处理：取出双重数组里层数据

   formatCardData = (listData = []) => {
   let itemsData = [];
    let cardCustomerData = [];
    for (let i = 0; i < listData.length; i++) {
      const data = listData[i];
      itemsData = data.items;
       cardCustomerData = [...cardCustomerData, ...itemsData];
     }
     return cardCustomerData;
   }

调用

this.formatCardData(res.data.result)