Non-Index Keys

Return an array of an object's own enumerable property names which are not integer indices.

Installation

npm install @stdlib/utils-nonindex-keys

Usage

var nonIndexKeys = require( '@stdlib/utils-nonindex-keys' );

nonIndexKeys( obj )

Returns an array of an object's own enumerable property names which are not integer indices.

var arr = [ 1, 2, 3 ];
arr.a = 'foo';
arr.b = 'bar';

var keys = nonIndexKeys( arr );
// e.g., returns [ 'a', 'b' ]

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.
• In contrast to the built-in Object.keys(), if provided null or undefined, the function returns an empty array, rather than throwing an error.

Examples

var nonIndexKeys = require( '@stdlib/utils-nonindex-keys' );

function Foo() {
    this[ 0 ] = 3.14;
    this.beep = 'boop';
    this.a = {
        'b': 'c'
    };
    return this;
}

Foo.prototype.foo = [ 'bar' ];

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

console.log( keys );
// e.g., => [ 'beep', 'a' ]

See Also

• @stdlib/utils-entries: return an array of an object's own enumerable property key-value pairs.
• @stdlib/utils-keys: return an array of an object's own enumerable property names.
• @stdlib/utils-values: return an array of an object's own enumerable property values.

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

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.