使用 lodash 压缩两个对象，其中一个对象的键和另一个对象的值

Question

我有对象 A 和 B 像这样：

const A = { a: 'foo', b: 'bar', c: 'baz' };
const B = { a: 'aaa', b: 'bbb', c: 'ccc' };

我需要将这两个转换为一个对象，其中键来自 A，值来自 B：

{ foo: 'aaa', bar: 'bbb', baz: 'ccc' }

如何用 lodash 做到这一点？

Answer 1

将对象转换为 [key, value] 对，展平为单个数组，然后按第一个元素（原始键）分组，将组映射到对数组，然后转换回对象。

使用 lodash/fp：

const { rest, flow, map, toPairs, flatten, groupBy, head, last, fromPairs } = _

const fn = rest(flow(
  map(toPairs), // map each object to pairs of [key, value]
  flatten, // flatten to a single array of pairs
  groupBy(head), // group the pairs by the key
  map(map(last)), // create a new pair by taking the last element of each pair in the group
  fromPairs // convert to an object
))

const A = { b: 'bar', c: 'baz', a: 'foo' }
const B = { a: 'aaa', b: 'bbb', c: 'ccc' }

const result = fn(A, B)

console.log(result)

<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'></script>

使用 lodash：

const { rest, flow, map, toPairs, flatten, groupBy, head, last, fromPairs } = _

const fn = rest(flow(
  objs => map(objs, toPairs), // map each object to pairs of [key, value]
  flatten, // flatten to a single array of pairs
  pairs => groupBy(pairs, head), // group the pairs by the key
  groups => map(groups, group => map(group, last)), // create a new pair by taking the last element of each pair in the group
  fromPairs // convert to an object
))

const A = { b: 'bar', c: 'baz', a: 'foo' }
const B = { a: 'aaa', b: 'bbb', c: 'ccc' }

const result = fn(A, B)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js" integrity="sha512-WFN04846sdKMIP5LKNphMaWzU7YpMyCU245etK3g/2ARYbPK9Ub18eG+ljU96qKRCWh+quCY7yefSmlkQw1ANQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>