npm package: @stdlib/utils-flatten-object
Description: Flatten an object.
Author: The Stdlib Authors
Latest version: 0.2.3

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</details>

# Flatten Object

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

> Flatten an object.

<section class="installation">

## Installation

```bash
npm install @stdlib/utils-flatten-object
```

</section>

<section class="usage">

## Usage

```javascript
var flattenObject = require( '@stdlib/utils-flatten-object' );
```

<a name="flatten-object"></a>

#### flattenObject( obj\[, options] )

Flattens an `object`.

```javascript
var obj = {
    'a': {
        'b': {
            'c': 'd'
        }
    }
};

var out = flattenObject( obj );
// returns { 'a.b.c': 'd' }
```

The function accepts the following `options`:

-   **depth**: maximum depth to flatten.
-   **copy**: `boolean` indicating whether to deep [copy][@stdlib/utils/copy] property values. Default: `false`.
-   **delimiter**: key path delimiter. Default: `'.'`.
-   **flattenArrays**: `boolean` indicating whether to flatten `arrays`. Default: `false`.

To flatten to a specified depth, set the `depth` option.

```javascript
var obj = {
    'a': {
        'b': {
            'c': 'd'
        }
    }
};

var out = flattenObject( obj, {
    'depth': 1
});
// returns { 'a.b': {'c': 'd'} }

var bool = ( obj.a.b === out['a.b'] );
// returns true
```

To deep [copy][@stdlib/utils/copy] property values, set the `copy` option to `true`.

```javascript
var obj = {
    'a': {
        'b': {
            'c': 'd'
        }
    }
};

var out = flattenObject( obj, {
    'depth': 1,
    'copy': true
});
// returns { 'a.b': { 'c': 'd' } }

var bool = ( obj.a.b === out['a.b'] );
// returns false
```

To specify a custom key path delimiter, set the `delimiter` option.

```javascript
var obj = {
    'a': {
        'b': {
            'c': 'd'
        }
    }
};

var out = flattenObject( obj, {
    'delimiter': '-|-'
});
// returns { 'a-|-b-|-c': 'd' }
```

By default, the function does **not** flatten `arrays`. To flatten `arrays`, set the `flattenArrays` option to `true`.

```javascript
var obj = {
    'a': {
        'b': [ 1, 2, 3 ]
    }
};

var out = flattenObject( obj, {
    'flattenArrays': true
});
// returns { 'a.b.0': 1, 'a.b.1': 2, 'a.b.2': 3 }
```

#### flattenObject.factory( options )

Returns a `function` to flatten an `object`.

```javascript
var flatten = flattenObject.factory({
    'delimiter': '|',
    'flattenArrays': true
});

var obj = {
    'a': {
        'b': {
            'c': 'd'
        }
    }
};

var out = flatten( obj );
// returns { 'a|b|c': 'd' }

obj = {
    'a': {
        'b': [ 1, 2, 3 ]
    }
};
out = flatten( obj );
// returns { 'a|b|0': 1, 'a|b|1': 2, 'a|b|2': 3 }
```

The function accepts the same `options` as [`flattenObject()`](#flatten-object).

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- TODO: update once Buffer wrapper -->

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

<!-- eslint-disable no-buffer-constructor -->

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var string2buffer = require( '@stdlib/buffer-from-string' );
var flattenObject = require( '@stdlib/utils-flatten-object' );

function noop() {
    // Do nothing...
}

var obj = {
    'a': {
        'b': {
            'beep': 'boop',
            'foo': 'bar'
        },
        'c': [ 1, 2, 3 ],
        'd': true,
        'e': null,
        'f': 3.14,
        'g': new Date(),
        'h': {
            'bip': 6,
            'bop': [ 4, 5, 6 ]
        },
        'i': [ null, true, {} ],
        'j': /.*/,
        'k': noop,
        'l': NaN,
        'm': [],
        'n': string2buffer( 'hello' ),
        'o': {
            'data': new Float64Array( 10 )
        },
        'p': {
            '1': {
                '2': {
                    '3': {}
                }
            }
        }
    }
};

var out = flattenObject( obj, {
    'depth': 5,
    'copy': true,
    'flattenArrays': false,
    'delimiter': '-|-'
});
/* returns
    {
        'a-|-b-|-beep': 'boop',
        'a-|-b-|-foo': 'bar',
        'a-|-c': [1,2,3],
        'a-|-d': true,
        'a-|-e': null,
        'a-|-f': 3.14,
        'a-|-g': <Date>,
        'a-|-h-|-bip': 6,
        'a-|-h-|-bop': [4,5,6],
        'a-|-i': [null,true,{}],
        'a-|-j': <RegExp>,
        'a-|-k': <Function>,
        'a-|-l': NaN,
        'a-|-m': [],
        'a-|-n': <Buffer>,
        'a-|-o-|-data': <Float64Array>,
        'a-|-p-|-1-|-2-|-3': {}
    }
*/
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/utils-flatten-array`][@stdlib/utils/flatten-array]</span><span class="delimiter">: </span><span class="description">flatten an array.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<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].

</section>

<!-- /.stdlib -->

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[umd]: https://github.com/umdjs/umd
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[deno-url]: https://github.com/stdlib-js/utils-flatten-object/tree/deno
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-flatten-object/main/LICENSE

[@stdlib/utils/copy]: https://www.npmjs.com/package/@stdlib/utils-copy

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

[@stdlib/utils/flatten-array]: https://www.npmjs.com/package/@stdlib/utils-flatten-array

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

</section>

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