npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

@stdlib/utils-copy

v0.2.2

Published

Copy or deep clone a value to an arbitrary depth.

Downloads

132,048

Readme

Copy

NPM version Build Status Coverage Status

Copy or deep clone a value to an arbitrary depth.

Installation

npm install @stdlib/utils-copy

Usage

var copy = require( '@stdlib/utils-copy' );

copy( value[, level] )

Copy or deep clone an input value to an arbitrary depth. The function accepts both objects and primitives.

// Primitives...
var out = copy( 'beep' );
// returns 'beep'

// Objects...
var value = [
    {
        'a': 1,
        'b': true,
        'c': [ 1, 2, 3 ]
    }
];
out = copy( value );
// returns [ { 'a': 1, 'b': true, 'c': [ 1, 2, 3 ] } ]

var bool = ( value[0].c === out[0].c );
// returns false

// Error object...
var err1 = new TypeError( 'beep' );

var err2 = copy( err1 );
// returns <TypeError>

The default behavior returns a full deep copy of any object. To limit the copy depth, set the level option.

var value = [
    {
        'a': 1,
        'b': true,
        'c': [ 1, 2, 3 ]
    }
];

// Trivial case => return the same reference
var out = copy( value, 0 );
// returns [ { 'a': 1, 'b': true, 'c': [ 1, 2, 3 ] } ]

var bool = ( value[0] === out[0] );
// returns true

// Shallow copy:
out = copy( value, 1 );

bool = ( value === out );
// returns false

bool = ( value[0] === out[0] );
// returns true

// Deep copy:
out = copy( value, 2 );

bool = ( value[0] === out[0] );
// returns false

bool = ( value[0].c === out[0].c );
// returns true

Notes

  • List of supported values/types:

  • List of unsupported values/types:

    • DOMElement: to copy DOM elements, use element.cloneNode().
    • Symbol
    • WeakMap
    • WeakSet
    • Blob
    • File
    • FileList
    • ImageData
    • ImageBitmap
    • ArrayBuffer
  • The implementation can handle circular references.

  • If a Number, String, or Boolean object is encountered, the value is cloned as a primitive. This behavior is intentional. The implementation is opinionated in wanting to avoid creating numbers, strings, and booleans via the new operator and a constructor.

  • For objects, the implementation only copies enumerable keys and their associated property descriptors.

  • The implementation only checks whether basic Objects, Arrays, and class instances are extensible, sealed, and/or frozen.

  • functions are not cloned; their reference is copied.

  • The implementation supports custom error types which are Error instances (e.g., ES2015 subclasses).

  • Support for copying class instances is inherently fragile. Any instances with privileged access to variables (e.g., within closures) cannot be cloned. This stated, basic copying of class instances is supported. Provided an environment which supports ES5, the implementation is greedy and performs a deep clone of any arbitrary class instance and its properties. The implementation assumes that the concept of level applies only to the class instance reference, but not to its internal state.

    function Foo() {
        this._data = [ 1, 2, 3, 4 ];
        this._name = 'bar';
        return this;
    }
    
    var foo1 = new Foo();
    var foo2 = copy( foo1 );
    
    var bool = ( foo1._name === foo2._name );
    // returns true
    
    bool = ( foo1._data === foo2._data );
    // returns false
    
    bool = ( foo1._data[0] === foo2._data[0] );
    // returns true

Examples

var randu = require( '@stdlib/random-base-randu' );
var Int32Array = require( '@stdlib/array-int32' );
var copy = require( '@stdlib/utils-copy' );

var arr = [
    {
        'x': new Date(),
        'y': [ randu(), randu() ],
        'z': new Int32Array( [ 1, 2, 3, 4 ] ),
        'label': 'Beep'
    },
    {
        'x': new Date(),
        'y': [ randu(), randu() ],
        'z': new Int32Array( [ 3, 1, 2, 4 ] ),
        'label': 'Boop'
    }
];

// Perform a full deep copy:
var out = copy( arr );

var bool = ( arr[ 0 ] === out[ 0 ] );
// returns false

bool = ( arr[ 1 ].y === out[ 1 ].y );
// returns false

// Perform a shallow copy:
out = copy( arr, 1 );

bool = ( arr[ 0 ] === out[ 0 ] );
// returns true

bool = ( arr[ 1 ].z === out[ 1 ].z );
// returns true

See Also


Notice

This package is part of 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, see the main project repository.

Community

Chat


License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.