---

title: '@corex/deepmerge' custom_edit_url: 'https://github.com/iamvishnusankar/corex/edit/master/packages/deepmerge/README.md'

A zero dependency object merger with typescript support and built in common merge utilities. Support merging of n number of objects

Installation

yarn add @corex/deepmerge

Usage

1import { merge } from '@corex/deepmerge'
2
3merge([obj1, obj2, obj3], { options })

Merge Options

property	default	description
arrayMergeType	combine	Merge two array by concatenation and remove duplicates. Available options are combine, overwrite
arrayMerge	-	Custom merge function to handle array merging.

Simple Object Merge

1const obj1 = {
2  a: 1,
3  b: {
4    c: 2,
5  },
6}
7
8const obj2 = {
9  a: 2,
10  b: {
11    c: 4,
12    d: 5,
13  },
14}
15
16const result = merge([obj1, obj2])
17console.log(result)
18
19// {
20//   a: 2,
21//   b: {
22//     c: 4,
23//     d: 5,
24//   },
25// }

Array Merge

1const arr1 = {
2  a: [1, 2, 3],
3}
4const arr2 = {
5  a: [3, 4, 5],
6}
7
8const result = merge([arr1, arr2])
9console.log(result)
10
11// result = {
12//   a: [1, 2, 3, 4, 5],
13// }

Complex Merge

1const obj1 = {
2  a: 2,
3  b: (x: number, y: number) => x + y,
4  c: [1, 2, 4],
5  d: {
6    e: [4, 5, 7],
7  },
8}
9
10console.log(obj1.b(7, 5)) // ==> 12
11
12const obj2 = {
13  a: 10,
14  b: (x: number, y: number) => x / y,
15  c: [20, 30],
16  d: {
17    e: [4, 7, 5],
18    f: {
19      g: 'another',
20    },
21  },
22}
23
24const obj3 = {
25  b: (x: number, y: number) => x * y,
26  c: [1, 2, 4],
27  d: {
28    e: [4, 7, 5],
29  },
30}
31
32const result = merge([obj1, obj2, obj3])
33
34console.log(result.b(7, 5)) // ==> 35

Array merge types

By default @corex/deepmerge uses combine merge. However user can implement their own methods to perform merge or use the built in overwrite.

Overwrite merge

1const obj1 = {
2  a: [1, 2, 3],
3  b: ['c', 'd'],
4  c: {
5    d: [1, 2],
6  },
7}
8
9const obj2 = {
10  a: [1, 7, 6],
11  b: ['e', 'f'],
12  c: {
13    d: [9, 10],
14  },
15}
16
17const obj3 = {
18  a: [20, 40],
19}
20
21const result = merge([obj1, obj2, obj3], {
22  arrayMergeType: 'overwrite',
23})
24console.log(result)
25
26// result = {
27//   a: [20, 40],
28//   b: ['e', 'f'],
29//   c: {
30//     d: [9, 10],
31//   },
32// }

Custom merge function

1const obj1 = {
2  a: ['1', '2'],
3  c: {
4    d: [1000, 500],
5  },
6}
7
8const obj2 = {
9  a: ['4', '5'],
10  c: {
11    d: [60, 80],
12  },
13}
14
15const customMergeFn = (_: any[], __: any[]) => 42
16
17const result = merge([obj1, obj2], {
18  arrayMerge: customMergeFn,
19})
20console.log(result)
21
22// {
23//   a: 42,
24//   c: {
25//     d: 42,
26//   },
27// }