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isNonConfigurablePropertyIn

Test if an object's own or inherited property is non-configurable.

Installation

npm install @stdlib/assert-is-nonconfigurable-property-in

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 isNonConfigurablePropertyIn = require( '@stdlib/assert-is-nonconfigurable-property-in' );

isNonConfigurablePropertyIn( value, property )

Returns a boolean indicating if a value has a non-configurable property (i.e., a property which cannot be deleted and whose descriptor cannot be changed).

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

var bool;
var obj;

function Foo() {
    this.foo = 'bar';
    return this;
}

defineProperty( Foo.prototype, 'beep', {
    'configurable': true,
    'enumerable': true,
    'writable': true,
    'value': true
});

defineProperty( Foo.prototype, 'boop', {
    'configurable': false,
    'enumerable': true,
    'writable': true,
    'value': true
});

obj = new Foo();

bool = isNonConfigurablePropertyIn( obj, 'foo' );
// returns false

bool = isNonConfigurablePropertyIn( obj, 'beep' );
// returns false

bool = isNonConfigurablePropertyIn( obj, 'boop' );
// returns true

Notes

Value arguments other than null or undefined are coerced to objects.

var bool = isNonConfigurablePropertyIn( 'beep', 'length' );
// returns true

Non-symbol property arguments are coerced to strings.

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

var obj = {};

defineProperty( obj, 'null', {
    'configurable': false,
    'enumerable': true,
    'writable': true,
    'value': true
});

var bool = isNonConfigurablePropertyIn( obj, null );
// returns true

Examples

var isNonConfigurablePropertyIn = require( '@stdlib/assert-is-nonconfigurable-property-in' );

var bool = isNonConfigurablePropertyIn( [ 'a' ], 'length' );
// returns true

bool = isNonConfigurablePropertyIn( {}, 'toString' );
// returns false

bool = isNonConfigurablePropertyIn( {}, 'hasOwnProperty' );
// returns false

bool = isNonConfigurablePropertyIn( { 'a': 'b' }, 'a' );
// returns false

bool = isNonConfigurablePropertyIn( [ 'a' ], 0 );
// returns false

bool = isNonConfigurablePropertyIn( { 'null': false }, null );
// returns false

bool = isNonConfigurablePropertyIn( { '[object Object]': false }, {} );
// returns false

bool = isNonConfigurablePropertyIn( null, 'a' );
// returns false

bool = isNonConfigurablePropertyIn( void 0, 'a' );
// returns false

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.

stdlib-js/assert-is-nonconfigurable-property-in