数组中的每个对象添加属性

let arr = [
{'name': 'aa', 'age': 10},
{'name': 'bb', 'age': 12}
]
let newArr = []
arr.map((item, index) => {
  newArr.push(
    Object.assign(item, { id: index} )
  ) 
})
console.log('arr', arr) // [ {'name': 'aa', 'age': 10},{'name': 'bb', 'age': 12}]

console.log('newArr', newArr)
// [ {name: "aa", age: 10, id: 0},{name: "bb", age: 12, id: 1}]