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inheritedPropertyDescriptor

Return a property descriptor for an object's inherited property.

Installation

npm install @stdlib/utils-inherited-property-descriptor

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 inheritedPropertyDescriptor = require( '@stdlib/utils-inherited-property-descriptor' );

inheritedPropertyDescriptor( obj, property[, level] )

Returns a property descriptor for an object's inherited property.

function Foo() {
    return this;
}

Foo.prototype.bar = 'foo';

var obj = new Foo();

var desc = inheritedPropertyDescriptor( obj, 'bar' );
// returns {'configurable':true,'enumerable':true,'writable':true,'value':'foo'}

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.beep = 'boop';

function Foo() {
    Bar.call( this );
    return this;
}

inherit( Foo, Bar );

var f = new Foo();
var desc = inheritedPropertyDescriptor( f, 'beep', 1 );
// returns null

Notes

• This function differs from the built-in Object.getOwnPropertyDescriptor() as follows:

  • If provided null or undefined, the function returns null, rather than throwing an error.
  • If an object does not have a provided inherited property, the function returns null, rather than undefined.

Examples

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

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

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

var obj = new Foo();
var desc = inheritedPropertyDescriptor( obj, 'foo' );

console.log( desc );
// => {'configurable':true,'enumerable':true,'writable':true,'value':['bar']}

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See Also

• @stdlib/utils-property-descriptor: return a property descriptor for an object's own property.
• @stdlib/utils-property-descriptor-in: return a property descriptor for an object's own or inherited property.
• @stdlib/utils-inherited-keys: return an array of an object's inherited enumerable property names.
• @stdlib/utils-inherited-property-descriptors: return an object's inherited property descriptors.
• @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.