inheritedPropertyDescriptor

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

Installation

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

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']}

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.

@stdlib/utils-inherited-property-descriptor

Package Exports

Readme