lodash.merge

What is lodash.merge?

The lodash.merge npm package is a method provided by lodash, a popular JavaScript utility library. It is used to recursively merge own and inherited enumerable string keyed properties of source objects into the destination object. It's commonly used to combine configurations, defaults, or to merge JSON objects with a deep copy.

What are lodash.merge's main functionalities?

Deep merging of objects

This feature allows for the deep merging of nested objects, combining properties from both source and destination objects.

{"const object = { 'a': [{ 'b': 2 }, { 'd': 4 }] };
const other = { 'a': [{ 'c': 3 }, { 'e': 5 }] };

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }"}

Merging with customizer function

This feature allows users to specify a customizer function that determines how merging is handled. It's useful for custom merge behavior on specific properties.

{"function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

const object = { 'a': [1], 'b': [2] };
const other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }"}

Other packages similar to lodash.merge

deepmerge

Deepmerge is an npm package that provides deep merging of objects and arrays. It is similar to lodash.merge but is more focused on deep merging without the rest of lodash's utility functions.

extend

Extend is a port of the classic jQuery.extend method that allows for deep or shallow copying of properties from one object to another. It is less powerful than lodash.merge for deep merging but is a lightweight alternative.

object-assign-deep

object-assign-deep npm package is similar to Object.assign but with deep merging capabilities. It is a smaller utility compared to lodash.merge and is focused solely on object merging.

README

lodash.merge v3.0.1

The modern build of lodash’s _.merge exported as a Node.js/io.js module.

Installation

Using npm:

$ {sudo -H} npm i -g npm
$ npm i --save lodash.merge

In Node.js/io.js:

var merge = require('lodash.merge');

See the documentation or package source for more details.