@stdlib/utils-deep-set NPM

Deep Set

Set a nested property value.

Installation

npm install @stdlib/utils-deep-set

Usage

var deepSet = require( '@stdlib/utils-deep-set' );

deepSet( obj, path, value[, options] )

Sets a nested property value.

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

var bool = deepSet( obj, 'a.b.c', 'beep' );
// returns true

console.log( obj );
// => { 'a': { 'b': { 'c': 'beep' } } }

If the function is able to deep set a nested property, the function returns true; otherwise, the function returns false.

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

var bool = deepSet( obj, 'a.b.c', 'woot' );
// returns true

bool = deepSet( obj, 'a.beep.c', 'boop' );
// returns false

bool = deepSet( null, 'a.beep.c', 'boop' );
// returns false

bool = deepSet( 'bap', 'a.beep.c', 'boop' );
// returns false

For paths including arrays, specify the numeric index.

var arr = [
    { 'a': [ { 'x': 5 } ] },
    { 'a': [ { 'x': 10 } ] }
];

var bool = deepSet( arr, '1.a.0.x', 25 );
// returns true

console.log( arr );
/* =>
    [
        { 'a': [ { 'x': 5 } ] },
        { 'a': [ { 'x': 25 } ] }
    ]
*/

The key path may be specified as either a delimited string or a key array.

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

var bool = deepSet( obj, [ 'a', 'b', 'c' ], 'beep' ); // obj => { 'a': { 'b': { 'c': 'beep' } } }
// returns true

If value is a function, the argument is treated as a callback and should return a value to set.

function set( val ) {
    var ch = val;
    var i;
    for ( i = 0; i < 4; i++ ) {
        val += ch;
    }
    return val;
}
var obj = { 'a': { 'b': { 'c': 'd' } } };

var bool = deepSet( obj, 'a.b.c', set ); // obj => { 'a': { 'b': { 'c': 'ddddd' } } }
// returns true

The function accepts the following options:

sep: key path separator. Default: '.'.
create: boolean indicating whether to create a path if the key path does not already exist. Default: false.

By default, the function assumes dot separated key values. To specify an alternative separator, set the sep option.

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

var bool = deepSet( obj, 'a/b/c', 'beep', {
    'sep': '/'
});
// returns true

console.log( obj );
// => { 'a': { 'b': { 'c': 'beep' } } }

To create a key path which does not already exist, set the create option to true.

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

var bool = deepSet( obj, 'a.e.c', 'boop', {
    'create': true
});
// returns true

console.log( obj );
/* =>
    {
        'a': {
            'b': {
                'c': 'beep'
            },
            'e': {
                'c': 'boop'
            }
        }
    }
*/

deepSet.factory( path[, options] )

Creates a reusable deep set function. The factory method ensures a deepSet function is configured identically by using the same set of provided options.

var dset = deepSet.factory( 'a/b/c', {
    'create': true,
    'sep': '/'
});

dset( obj, value )

Sets a nested property value.

var dset = deepSet.factory( 'a.b.c' );

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

var bool = dset( obj, 'beep' );
// returns true

console.log( obj );
// => { 'a': { 'b': { 'c': 'beep' } } }

Examples

var randu = require( '@stdlib/random-base-randu' );
var deepSet = require( '@stdlib/utils-deep-set' );

var data;
var bool;
var keys;
var i;

function set( val ) {
    return val * 10.0;
}

data = new Array( 100 );
for ( i = 0; i < data.length; i++ ) {
    data[ i ] = {
        'x': Date.now(),
        'y': [ randu(), randu(), i ]
    };
}

keys = [ 0, 'y', 2 ];
for ( i = 0; i < data.length; i++ ) {
    keys[ 0 ] = i;
    bool = deepSet( data, keys, set );
    if ( !bool ) {
        console.error( 'Unable to deep set value.' );
    }
}
console.log( data );

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.