@stdlib/utils-inherited-keys NPM

inheritedKeys

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

Installation

npm install @stdlib/utils-inherited-keys

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' ]

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.