Deep Set

    Set a nested property value.

    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 );