Rect getRectValue( ) throws DOMException;
The Rect object that represents the value of this CSSPrimitiveValue.
This method throws a DOMException with a code of INVALID_ACCESS_ERR if the primitiveType property is not CSS_RECT.
This method returns a Rect object that represents a CSS rectangle. There is no corresponding setRectValue( ) method, but you can modify the value by setting the properties of the returned Rect object.