Lodash - 选择不在数组中的元素[重复]

Question

我有以下数组：

[
  {
    id: 1
  },
  {
    id: 2
  },
  {
    id: 3
  },
  {
    id: 4
  }
]

我的应用程序每 5 秒收到一个新数组，我需要比较下一个数组之间的差异...

所以下一个数组是：

[
  {
    id: 1
  },
  {
    id: 2
  },
  {
    id: 4
  }
]

如何与前一个比较，得到一个包含排除项的数组？

[
  {
    id: 3
  }
]

---

正确的问题

Lodash - DifferenceBy with different identity

Answer 1

如果您想根据id 找到差异，可以使用 Lodash differenceBy 方法并传递 id 属性。否则你可以使用_.differenceWith(prev, next, _.isEqual)

const prev = [{"id":1},{"id":2},{"id":3},{"id":4}]
const next = [{"id":1},{"id":2},{"id":4}]

const diff = _.differenceBy(prev, next, 'id')
console.log(diff)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>

如果您想检查不同的键或 id 属性名称，您可以使用 differenceWith 并通过自定义相等检查功能。

const prev = [{"id":1},{"id":2},{"id":3},{"id":4}]
const next = [{"contact_id":1},{"contact_id":2},{"contact_id":4}]

const checkId = (prev, next) => {
  return prev.id == next.contact_id
}

const diff = _.differenceWith(prev, next, checkId)
console.log(diff)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>