inheritedPropertyDescriptor

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

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']}