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inheritedKeys

Return an array of an object's inherited enumerable property names.

Installation

npm install @stdlib/utils-inherited-keys

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 inheritedKeys = require( '@stdlib/utils-inherited-keys' );

inheritedKeys( obj[, level] )

Returns an array of an object's inherited enumerable property names.

function Foo() {
    this.a = 'b';
    return this;
}

Foo.prototype.beep = 'boop';

var f = new Foo();
var keys = inheritedKeys( f );
// returns [ 'beep' ]

By default, the function walks an object's entire prototype chain. To limit the inheritance level, provide a level argument.

var inherit = require( '@stdlib/utils-inherit' );

function Bar() {
    return this;
}

Bar.prototype.boop = 'beep';

function Foo() {
    Bar.call( this );
    this.a = 'b';
    return this;
}

inherit( Foo, Bar );
Foo.prototype.beep = 'boop';

var f = new Foo();
var keys = inheritedKeys( f, 1 );
// returns [ 'beep' ]

Notes

• Name order is not guaranteed, as object key enumeration is not specified according to the ECMAScript specification. In practice, however, most engines use insertion order to sort an object's keys, thus allowing for deterministic extraction.

Examples

var defineProperty = require( '@stdlib/utils-define-property' );
var inheritedKeys = require( '@stdlib/utils-inherited-keys' );

function Foo() {
    this.beep = 'boop';
    this.a = {
        'b': 'c'
    };
    defineProperty( this, 'baz', {
        'configurable': false,
        'enumerable': false,
        'writable': true,
        'value': 'qux'
    });
    return this;
}

Foo.prototype.foo = [ 'bar' ];
defineProperty( Foo.prototype, 'bip', {
    'configurable': false,
    'enumerable': false,
    'writable': false,
    'value': 'bop'
});

var obj = new Foo();
var keys = inheritedKeys( obj );

console.log( keys );
// => [ 'foo' ]

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See Also

• @stdlib/utils-keys: return an array of an object's own enumerable property names.
• @stdlib/utils-keys-in: return an array of an object's own and inherited enumerable property names.
• @stdlib/utils-inherited-property-names: return an array of an object's inherited enumerable and non-enumerable property names.
• @stdlib/utils-inherited-property-symbols: return an array of an object's inherited symbol properties.

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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 © 2016-2024. The Stdlib Authors.