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Flatten Object

Flatten an object.

Installation

npm install @stdlib/utils-flatten-object

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md 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

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

flattenObject( obj[, options] )

Flattens an object.

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 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.

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 property values, set the copy option to true.

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.

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.

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.

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().

Examples

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': {}
    }
*/

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See Also

• @stdlib/utils-flatten-array: flatten an array.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.