@stdlib/utils-merge

Merge and extend objects.

https://github.com/stdlib-js/utils-merge

Science Score: 44.0%

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Low similarity (14.7%) to scientific vocabulary

Keywords

array date deep deepextend deepmerge extend javascript merge node node-js nodejs object regexp shallow shallowmerge stdlib util utilities utils xtend

Keywords from Contributors

iterate accumulate names tokenizer reduce assert capitals inherited normalize abbreviate

Last synced: 6 months ago · JSON representation ·

Repository

Merge and extend objects.

Basic Info

Host: GitHub
Owner: stdlib-js
License: apache-2.0
Language: JavaScript
Default Branch: main
Homepage: https://github.com/stdlib-js/stdlib
Size: 1.82 MB

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array date deep deepextend deepmerge extend javascript merge node node-js nodejs object regexp shallow shallowmerge stdlib util utilities utils xtend

Created over 4 years ago · Last pushed 6 months ago

Metadata Files

Readme Changelog Contributing License Code of conduct Citation Security

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

Merge

Merge and extend objects.

## Installation ```bash npm install @stdlib/utils-merge ``` Alternatively, - To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]). - If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions). - For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]). The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships. To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

## Usage ```javascript var merge = require( '@stdlib/utils-merge' ); ``` #### merge( target, source1\[, source2\[,...,sourceN]] ) Merges and extends a target `object`. ```javascript var target = { 'a': 'beep' }; var source = { 'a': 'boop', 'b': 'bap' }; var out = merge( target, source ); /* returns { 'a': 'boop', 'b': 'bap' } */ ``` The function supports merging multiple source `objects`. ```javascript var target = { 'a': 'beep' }; var source1 = { 'b': 'boop' }; var source2 = { 'c': 'cat' }; var out = merge( target, source1, source2 ); /* returns { 'a': 'beep', 'b': 'boop', 'c': 'cat' } */ ``` #### merge.factory( options ) Returns a custom merge `function` for merging and extending `objects`. ```javascript var opts = { 'level': 100, 'copy': true, 'override': true, 'extend': true }; var m = merge.factory( opts ); ``` The function accepts the following `options`: - **level**: limits the merge depth. The default merge strategy is a deep (recursive) merge. Default: `+infinity`. - **copy**: `boolean` indicating whether to [deep copy][@stdlib/utils/copy] merged values. Deep copying prevents shared references and source `object` mutation. Default: `true`. - **override**: defines the merge strategy. If `true`, source `object` values will **always** override target `object` values. If `false`, source values **never** override target values (useful for adding, but not overwriting, properties). To define a custom merge strategy, provide a `function`. Default: `true`. - **extend**: `boolean` indicating whether new properties can be added to the target `object`. If `false`, only **shared** properties are merged. Default: `true`. The default merge is a deep (recursive) merge. ```javascript var m = merge.factory( {} ); var target = { 'a': { 'b': { 'c': 5 }, 'd': 'beep' } }; var source = { 'a': { 'b': { 'c': 10 } } }; var out = m( target, source ); /* returns { 'a': { 'b': { 'c': 10 }, 'd': 'beep' } } */ ``` To limit the merge depth, set the `level` option. ```javascript var m = merge.factory({ 'level': 2 }); var target = { '1': { 'a': 'beep', '2': { '3': null, 'b': [ 5, 6, 7 ] } } }; var source = { '1': { 'b': 'boop', '2': { '3': [ 1, 2, 3 ] } } }; var out = m( target, source ); /* returns { '1': { 'a': 'beep', 'b': 'boop', '2': { '3': [ 1, 2, 3 ] } } } */ ``` By default, merged values are [deep copied][@stdlib/utils/copy]. ```javascript var m = merge.factory( {} ); var target = { 'a': null }; var source = { 'a': { 'b': [ 1, 2, 3 ] } }; var out = m( target, source ); console.log( out.a.b === source.a.b ); // => false ``` To allow shared references, set the `copy` option to `false`. ```javascript var m = merge.factory({ 'copy': false }); var target = {}; var source = { 'a': [ 1, 2, 3 ] }; var out = m( target, source ); var bool = ( out.a === source.a ); // returns true ``` To prevent existing properties from being overridden, set the `override` option to `false`. ```javascript var m = merge.factory({ 'override': false }); var target = { 'a': 'beep', 'b': 'boop' }; var source = { 'a': null, 'c': 'bop' }; var out = m( target, source ); /* returns { 'a': 'beep', 'b': 'boop', 'c': 'bop' } */ ``` Alternatively, to define a custom merge strategy, set the `override` option to a `function`. ```javascript function strategy( a, b, key ) { /* Parameters: a => target value b => source value key => object key */ if ( key === 'a' ) { return b; } if ( key === 'b' ) { return a; } return 'bebop'; } var m = merge.factory({ 'override': strategy }); var target = { 'a': 'beep', 'b': 'boop', 'c': 1234 }; var source = { 'a': null, 'b': {}, 'c': 'bop' }; var out = m( target, source ); /* returns { 'a': null, 'b': 'boop', 'c': 'bebop' } */ ``` To prevent non-existent properties from being added to the target `object`, set the `extend` option to `false`. ```javascript var m = merge.factory({ 'extend': false }); var target = { 'a': 'beep', 'b': 'boop' }; var source = { 'b': 'hello', 'c': 'world' }; var out = m( target, source ); /* returns { 'a': 'beep', 'b': 'hello' } */ ```

* * * ## Notes - The target `object` is **mutated**. ```javascript var target = { 'a': 'beep' }; var source = { 'b': 'boop' }; var out = merge( target, source ); console.log( out === target ); // => true console.log( target.b ); // => 'boop' ``` To return a new `object`, provide an empty `object` as the first argument. ```javascript var target = { 'a': 'beep' }; var source = { 'b': 'boop' }; var out = merge( {}, target, source ); console.log( out === target ); // => false ``` - **Only** plain JavaScript `objects` are merged and extended. The following values/types are either [deep copied][@stdlib/utils/copy] or assigned: - `Boolean` - `String` - `Number` - `Date` - `RegExp` - `Array` - `Int8Array` - `Uint8Array` - `Uint8ClampedArray` - `Init16Array` - `Uint16Array` - `Int32Array` - `Uint32Array` - `Float32Array` - `Float64Array` - `Buffer` ([Node.js][node-buffer]) - `Set` - `Map` - `Error` - `URIError` - `ReferenceError` - `SyntaxError` - `RangeError` - Support for deep merging class instances is inherently [**fragile**][@stdlib/utils/copy]. - `Number`, `String`, or `Boolean` objects are merged as [primitives][@stdlib/utils/copy]. - Functions are **not** [deep copied][@stdlib/utils/copy].

* * * ## Examples ```javascript var merge = require( '@stdlib/utils-merge' ); var target = { 'a': 'beep', 'b': 'boop', 'c': { 'c1': 'woot', 'c2': false, 'c3': { 'c3a': [ 1, 2 ], 'c3b': null } }, 'd': [ 1, 2, 3 ] }; var source = { 'b': 3.141592653589793, 'c': { 'c1': 'bap', 'c3': { 'c3b': 5, 'c3c': 'bop' }, 'c4': 1337, 'c5': new Date() }, 'd': [ 4, 5, 6 ], 'e': true }; var out = merge( {}, target, source ); /* returns { 'a': 'beep', 'b': 3.141592653589793, 'c': { 'c1': 'bap', 'c2': false, 'c3': { 'c3a': [ 1, 2 ], 'c3b': 5, 'c3c': 'bop' }, 'c4': 1337, 'c5': }, 'd': [ 4, 5, 6 ], 'e': true } */ ```

* * * ## Notice This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more. For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib]. #### Community [![Chat][chat-image]][chat-url] --- ## License See [LICENSE][stdlib-license]. ## Copyright Copyright © 2016-2025. The Stdlib [Authors][stdlib-authors].

Owner

Name: stdlib
Login: stdlib-js
Kind: organization

Website: https://stdlib.io
Twitter: stdlibjs
Repositories: 3,692
Profile: https://github.com/stdlib-js

Standard library for JavaScript.

Citation (CITATION.cff)

cff-version: 1.2.0
title: stdlib
message: >-
  If you use this software, please cite it using the
  metadata from this file.

type: software

authors:
  - name: The Stdlib Authors
    url: https://github.com/stdlib-js/stdlib/graphs/contributors

repository-code: https://github.com/stdlib-js/stdlib
url: https://stdlib.io

abstract: |
  Standard library for JavaScript and Node.js.

keywords:
  - JavaScript
  - Node.js
  - TypeScript
  - standard library
  - scientific computing
  - numerical computing
  - statistical computing

license: Apache-2.0 AND BSL-1.0

date-released: 2016

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npmjs.org: @stdlib/utils-merge

Merge and extend objects.

Homepage: https://stdlib.io
License: Apache-2.0
Latest release: 0.2.2
published over 1 year ago

Versions: 11
Dependent Packages: 6
Dependent Repositories: 1
Downloads: 58 Last month

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planeshifter rreusser stdlib-bot kgryte

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@stdlib/array-uint8 ^0.0.x development
@stdlib/bench ^0.0.x development
@stdlib/boolean-ctor ^0.0.x development
@stdlib/buffer-from-string ^0.0.x development
@stdlib/number-ctor ^0.0.x development
@stdlib/random-base-randu ^0.0.x development
istanbul ^0.4.1 development
tap-spec 5.x.x development
tape git+https://github.com/kgryte/tape.git#fix/globby development
@stdlib/assert-has-own-property ^0.0.x
@stdlib/assert-is-boolean ^0.0.x
@stdlib/assert-is-buffer ^0.0.x
@stdlib/assert-is-function ^0.0.x
@stdlib/assert-is-object ^0.0.x
@stdlib/assert-is-plain-object ^0.0.x
@stdlib/assert-is-positive-integer ^0.0.x
@stdlib/constants-float64-pinf ^0.0.x
@stdlib/string-format ^0.0.x
@stdlib/types ^0.0.x
@stdlib/utils-copy ^0.0.x
@stdlib/utils-define-nonenumerable-read-only-property ^0.0.x
@stdlib/utils-keys ^0.0.x
@stdlib/utils-type-of ^0.0.x

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@stdlib/utils-merge

Science Score: 44.0%

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