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']}