# inheritedWritablePropertySymbols
> Return an array of an object's inherited writable [symbol][@stdlib/symbol/ctor] properties.
## Usage
```javascript
var inheritedWritablePropertySymbols = require( '@stdlib/utils/inherited-writable-property-symbols' );
```
#### inheritedWritablePropertySymbols( obj\[, level] )
Returns an `array` of an object's inherited writable [symbol][@stdlib/symbol/ctor] properties.
```javascript
var defineProperty = require( '@stdlib/utils/define-property' );
var hasSymbolSupport = require( '@stdlib/assert/has-symbol-support' );
var Symbol = require( '@stdlib/symbol/ctor' );
var hasSymbols = hasSymbolSupport();
var symbols;
var f;
function Foo() {
if ( hasSymbols ) {
defineProperty( this, Symbol( 'a' ), {
'configurable': false,
'enumerable': false,
'writable': true,
'value': 'a'
});
}
return this;
}
if ( hasSymbols ) {
defineProperty( Foo.prototype, Symbol( 'b' ), {
'configurable': false,
'enumerable': false,
'writable': true,
'value': 'b'
});
}
f = new Foo();
symbols = inheritedWritablePropertySymbols( f );
```
By default, the function walks an object's entire prototype chain. To limit the inheritance level, provide a `level` argument.
```javascript
var symbols = inheritedWritablePropertySymbols( [], 1 );
```
## Notes
- Property order is not guaranteed, as `object` property enumeration is not specified according to the [ECMAScript specification][ecma-262-for-in]. In practice, however, most engines use insertion order to sort an `object`'s properties, thus allowing for deterministic extraction.
## Examples
```javascript
var defineProperty = require( '@stdlib/utils/define-property' );
var hasSymbolSupport = require( '@stdlib/assert/has-symbol-support' );
var Symbol = require( '@stdlib/symbol/ctor' );
var inheritedWritablePropertySymbols = require( '@stdlib/utils/inherited-writable-property-symbols' );
var hasSymbols = hasSymbolSupport();
var symbols;
var obj;
function Foo() {
this.a = 'a';
defineProperty( this, 'b', {
'configurable': false,
'enumerable': false,
'writable': false,
'value': 'b'
});
if ( hasSymbols ) {
this[ Symbol( 'a' ) ] = 'a';
defineProperty( this, Symbol( 'b' ), {
'configurable': false,
'enumerable': false,
'writable': false,
'value': 'b'
});
}
return this;
}
Foo.prototype.c = 'c';
defineProperty( Foo.prototype, 'd', {
'configurable': false,
'enumerable': false,
'writable': false,
'value': 'd'
});
if ( hasSymbols ) {
Foo.prototype[ Symbol( 'c' ) ] = 'c';
defineProperty( Foo.prototype, Symbol( 'd' ), {
'configurable': false,
'enumerable': false,
'writable': false,
'value': 'd'
});
}
obj = new Foo();
symbols = inheritedWritablePropertySymbols( obj );
console.log( symbols );
```
[ecma-262-for-in]: http://www.ecma-international.org/ecma-262/5.1/#sec-12.6.4
[@stdlib/symbol/ctor]: https://www.npmjs.com/package/@stdlib/symbol-ctor