const dataList = ref([
  { num: 0, fieldKey: 'aValue', title: 'a' },
  { num: 0, fieldKey: 'bValue', title: 'b' },
]) as any;

const getData = async () => {
  let res = {
    aValue: 1,
    bValue: 2
  }
  dataList.value.forEach((item) => {
    item.num = res[item.fieldKey as any];
  });
  console.log(dataList.value); // [{ num: 1, fieldKey: 'aValue', title: 'a' }, { num: 2, fieldKey: 'bValue', title: 'b' }]

};