Extract a nested property value from each element of an object array.
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> Extract a nested property value from each element of an object array.
``bash`
npm install @stdlib/utils-deep-pluck
`javascript`
var deepPluck = require( '@stdlib/utils-deep-pluck' );
#### deepPluck( arr, path\[, options] )
Extracts a nested property value from each element of an object array based on a key path.
`javascript
var arr = [
{ 'a': { 'b': { 'c': 1 } } },
{ 'a': { 'b': { 'c': 2 } } }
];
var out = deepPluck( arr, 'a.b.c' );
// returns [ 1, 2 ]
`
A key path may be specified as either a string or as an array.
`javascript
var arr = [
{ 'a': [ 0, 1, 2 ] },
{ 'a': [ 3, 4, 5 ] }
];
var out = deepPluck( arr, [ 'a', 1 ] );
// returns [ 1, 4 ]
`
The function accepts the following options:
- copy: boolean indicating whether to return a new data structure. Default: true.'.'
- sep: key path [separator][@stdlib/object/deep-get]. Default: .
By default, the function returns a new data structure. To mutate the input data structure (e.g., when input values can be discarded or when optimizing memory usage), set the copy option to false.
`javascript
var arr = [
{ 'a': { 'b': { 'c': 1 } } },
{ 'a': { 'b': { 'c': 2 } } }
];
var out = deepPluck( arr, 'a.b.c', { 'copy': false } );
// returns [ 1, 2 ]
var bool = ( arr[ 0 ] === out[ 0 ] );
// returns true
`
The default key path separator is .. To specify an alternative separator, set the sep option.
`javascript
var arr = [
{ 'a': { 'b': { 'c': 1 } } },
{ 'a': { 'b': { 'c': 2 } } }
];
var out = deepPluck( arr, 'a|b|c', { 'sep': '|' } );
// returns [ 1, 2 ]
`
- If a key path does not exist, the function sets the plucked value as undefined.
`javascript
var arr = [
{ 'a': { 'b': { 'c': 1 } } },
null,
void 0,
{ 'a': { 'b': { 'c': 2 } } }
];
var out = deepPluck( arr, 'a.b.c' );
// returns [ 1, undefined, undefined, 2 ]
`
- Extracted values are not cloned.
`javascript
var arr = [
{ 'a': { 'b': { 'c': 2 } } },
{ 'a': { 'b': { 'c': 3 } } }
];
var out = deepPluck( arr, 'a.b' );
// returns [ { 'c': 2 }, { 'c': 3 } ]
var bool = ( arr[ 0 ].a.b === out[ 0 ] );
// returns true
`
To prevent subsequent unintended mutation, use [copy][@stdlib/utils/copy].
`javascript
var copy = require( '@stdlib/utils-copy' );
var arr = [
{ 'a': { 'b': { 'c': 2 } } },
{ 'a': { 'b': { 'c': 3 } } }
];
var out = deepPluck( arr, 'a.b' );
// returns [ { 'c': 2 }, { 'c': 3 } ]
// Perform a deep copy:
out = copy( out );
var bool = ( arr[ 0 ].a.b === out[ 0 ] );
// returns false
`
`javascript
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var deepPluck = require( '@stdlib/utils-deep-pluck' );
var arr;
var out;
var tmp;
var i;
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
tmp = {
'a': {
'b': {
'c': {
'd': null
}
}
}
};
tmp.a.b.c.d = round( randu()*100.0 );
arr[ i ] = tmp;
}
// Pluck the deeply nested values:
out = deepPluck( arr, 'a.b.c.d' );
console.log( out );
`
*
- [@stdlib/object-deep-get][@stdlib/object/deep-get]: get a nested property value.
- [@stdlib/object-deep-set][@stdlib/object/deep-set]: set a nested property value.
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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