javascript - 合并/操作对象数组

Question

我有一个如下所示的对象数组:

[{
  animal: "cat",
  dateString: "2017-01-03"
},{
  animal: "dog",
  dateString: "2017-02-05"
},{
  animal: "cat",
  dateString: "2017-03-04"
}]

我想创建一个如下所示的新数组:

[{
  animal: "cat",
  values: [
    "2017-01-03",
    "2017-03-04"
  ]
},{
  animal: "dog",
  values: [
    "2017-02-05"
  ]
}]

如何将各个对象属性合并到值数组中？

Answer 1

没有 lodash/ramda 你也能做到

const a = [
  {
    animal: 'cat',
    dateString: '2017-01-03'
  }, {
    animal: 'dog',
    dateString: '2017-02-05'
  }, {
    animal: 'cat',
    dateString: '2017-03-04'
  }
]

const b = Object.values(a.reduce((a, b) => {
  if (a[b.animal]) {
    a[b.animal].values.push(b.dateString)
  } else {
    a[b.animal] = {animal: b.animal, values: [b.dateString]}
  }
  return a
}, {}))