npm package: @stdlib/object-lowercase-keys
Description: Convert each object key to lowercase.
Author: The Stdlib Authors
Latest version: 0.1.1

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# lowercaseKeys

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Convert each object key to lowercase.

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/object-lowercase-keys
```

</section>

<section class="usage">

## Usage

```javascript
var lowercaseKeys = require( '@stdlib/object-lowercase-keys' );
```

#### lowercaseKeys( obj )

Converts each `object` key to lowercase, mapping the transformed keys to a new `object` having the same values.

```javascript
var obj1 = {
    'A': 1,
    'B': 2
};

var obj2 = lowercaseKeys( obj1 );
// returns { 'a': 1, 'b': 2 }
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   The function only transforms **own** properties. Hence, the function does **not** transform inherited properties.
-   The function **shallow** copies key values.

</section>

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<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var lowercaseKeys = require( '@stdlib/object-lowercase-keys' );

var obj1 = {
    'A': 'beep',
    'B': 'boop',
    'C': 'foo',
    'D': 'bar'
};

var obj2 = lowercaseKeys( obj1 );

console.dir( obj2 );
// => { 'a': 'beep', 'b': 'boop', 'c': 'foo', 'd': 'bar' }
```

</section>

<!-- /.examples -->

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* * *

## See Also

-   <span class="package-name">[`@stdlib/object-uncapitalize-keys`][@stdlib/object/uncapitalize-keys]</span><span class="delimiter">: </span><span class="description">convert the first letter of each object key to lowercase.</span>
-   <span class="package-name">[`@stdlib/object-uppercase-keys`][@stdlib/object/uppercase-keys]</span><span class="delimiter">: </span><span class="description">convert each object key to uppercase.</span>

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## 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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[npm-image]: http://img.shields.io/npm/v/@stdlib/object-lowercase-keys.svg
[npm-url]: https://npmjs.org/package/@stdlib/object-lowercase-keys

[test-image]: https://github.com/stdlib-js/object-lowercase-keys/actions/workflows/test.yml/badge.svg?branch=v0.1.1
[test-url]: https://github.com/stdlib-js/object-lowercase-keys/actions/workflows/test.yml?query=branch:v0.1.1

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/object-lowercase-keys/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/object-lowercase-keys?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/object-lowercase-keys/tree/deno
[deno-readme]: https://github.com/stdlib-js/object-lowercase-keys/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/object-lowercase-keys/tree/umd
[umd-readme]: https://github.com/stdlib-js/object-lowercase-keys/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/object-lowercase-keys/tree/esm
[esm-readme]: https://github.com/stdlib-js/object-lowercase-keys/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/object-lowercase-keys/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/object-lowercase-keys/main/LICENSE

<!-- <related-links> -->

[@stdlib/object/uncapitalize-keys]: https://www.npmjs.com/package/@stdlib/object-uncapitalize-keys

[@stdlib/object/uppercase-keys]: https://www.npmjs.com/package/@stdlib/object-uppercase-keys

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</section>

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