$() || 'Bartłomiej' 
will result in jQuery object
as empty jquery object is truthy
```
$( '#wkTOC.side-menu, #wkTOCHandle' ).eq(0) will do what you're trying to do
```
or 
```
elmToHide = $( '#wkTOC.side-menu' );
if ( !elmToHide.length ) { 
    elmToHide = $( '#wkTOCHandle' )
}
```