node package manager
Painless code sharing. npm Orgs help your team discover, share, and reuse code. Create a free org »



build status dependency status

browser support

Deep merge objects with custom merging logic


Use deep-extend instead of this module.


When you create a merge "strategy" you can configure how two values should merge when they have the same key. For example you may want them to be combined into a single array.

var DeepMerge = require("deep-merge")
var assert = require("assert")
var merge = DeepMerge(function mergeStrategy(target, source, key) {
    return [].concat(target, source)
var res = merge({
    foo: ["hello"]
}, {
    foo: "goodbye"
assert.deepEqual(res, { foo: ["hello", "goodbye"] })

By default objects will recursely call your mergeStrategy on your the values for a key and construct a new object with the key and the value returned from your merge

Merging multiple objects

var DeepMerge = require("deep-merge/multiple")
var merge = DeepMerge(function (a, b) {
    return b
var obj = merge([
    { a: "a" },
    { b: "b" },
    { c: { d: "d" } },
    { c: { e: "e" } }
assert.deepEqual(obj.c, { d: "d", e: "e" })


npm install deep-merge


  • Raynos

MIT Licenced