Javascript 对象不附加新属性

Question

我有这个函数，我在其中检索一个对象数组，然后我有一个 for 循环来遍历对象，并向它附加一个索引或 ind 属性:

module.exports.getCustomers = async (req, res) => {
  let customers = await Customers.find({}, { "_id": 1 });

  for (var i = 0; i < customers.length; i++) {
    customers[i].ind = i;
  }

  console.log(customers)
}

但是当我运行它时，数据返回为

[
  { _id: ... },
  { _id: ... },
  ...
]

代替:

[
   {_id: ..., ind: 0},
   {_id: ..., ind: 1},
   ...
]

请问我该如何解决

Answer 1

更改您的 for 并将其转换为 map

module.exports.getCustomers = async (req, res) => {
  let customers = await Customers.find({}, { "_id": 1 });

  let mappedCustomers = customers.map((customer, index) => {
              customer['ind'] = index;
              return customer;
          });


  console.log(mappedCustomers);
  return mappedCustomers;
}

或者代替返回客户，您可以创建一个全新的客户。

let mappedCustomers = customers.map((customer, index) => {
              return {...customer, ind: index};
              });