deep merge

about.md

Comparison

name	immutable	concat	dedupe	clone	multiple parameters	recommended
merge-deep@3.0.2	true	true	true	true	yes	yes
deepmerge@3.0.0	true	true	false	false(option)	no
lodash/mege	false	false	false	true	yes
lodash/megeWith	false	false	false	true	yes	yes

• https://www.npmjs.com/package/merge-deep
• https://www.npmjs.com/package/deepmerge
• https://lodash.com/docs/4.17.11#mergeWith

Usage

merge-deep:

mergeDeep(...objects)

deepmerge:

deepmerge(a, b, {clone: false})
deepmerge.all([a, b, c], {clone: false})

lodash:

const concatMerge = (...args) => mergeWith({}, ...args, (dest, src) => {
  if (Array.isArray(dest)) {
    return dest.concat(src)
  }
})

test.js

const mergeDeep = require('merge-deep')
const deepMerge = require('deepmerge')

const merge = require('lodash/merge')
const mergeWith = require('lodash/mergeWith')
const partialRight = require('lodash/partialRight')

const concatMerge = partialRight(mergeWith, (prev, next) => {
  if (Array.isArray(prev)) {
    return prev.concat(next)
  }
})

class Plugin {
  constructor(props) {
    Object.assign(this, props)
  }
}

const test = (merge, name) => {
  const dest = {foo: [1, 2], plugins: [new Plugin({a: 1})]}
  const src = {foo: [1, 3], plugins: [new Plugin({a: 2})]}
  const result = merge(dest, src)

  const immutable = result !== dest
  return {
    name,
    immutable,
    concat: result.foo.length >= 3,
    dedupe: result.foo.length === 3,
    clone: result.plugins.every(plugin => plugin instanceof Plugin),
    result: JSON.stringify(result),
  }
}

console.info([
  test(mergeDeep, 'mergeDeep'),
  test(deepMerge, 'deepMerge'),
  test(merge, 'lodash/merge'),
  test(mergeWith, 'lodash/mergeWith'),
  // custom
  test(concatMerge, 'lodash/mergeWith --concat'),
  test((...args) => deepMerge(...args, {clone: false}), 'deepMerge --no-clone'),
])