inheritedKeys

    Return an array of an object's inherited enumerable property names.

    Usage

    var inheritedKeys = require( '@stdlib/utils/inherited-keys' );
    

    inheritedKeys( obj[, level] )

    Returns an array of an object's inherited enumerable property names.

    function Foo() {
        this.a = 'b';
        return this;
    }
    
    Foo.prototype.beep = 'boop';
    
    var f = new Foo();
    var keys = inheritedKeys( f );
    // returns [ 'beep' ]
    

    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.boop = 'beep';
    
    function Foo() {
        Bar.call( this );
        this.a = 'b';
        return this;
    }
    
    inherit( Foo, Bar );
    Foo.prototype.beep = 'boop';
    
    var f = new Foo();
    var keys = inheritedKeys( f, 1 );
    // returns [ 'beep' ]
    

    Notes

    • Name order is not guaranteed, as object key enumeration is not specified according to the ECMAScript specification. In practice, however, most engines use insertion order to sort an object's keys, thus allowing for deterministic extraction.

    Examples

    var defineProperty = require( '@stdlib/utils/define-property' );
    var inheritedKeys = require( '@stdlib/utils/inherited-keys' );
    
    function Foo() {
        this.beep = 'boop';
        this.a = {
            'b': 'c'
        };
        defineProperty( this, 'baz', {
            'configurable': false,
            'enumerable': false,
            'writable': true,
            'value': 'qux'
        });
        return this;
    }
    
    Foo.prototype.foo = [ 'bar' ];
    defineProperty( Foo.prototype, 'bip', {
        'configurable': false,
        'enumerable': false,
        'writable': false,
        'value': 'bop'
    });
    
    var obj = new Foo();
    var keys = inheritedKeys( obj );
    
    console.log( keys );
    // => [ 'foo' ]