No, vJASS introduces the use of methods into JASS which allows for a more powerful programming language.
JASS is already an OO Scripting Language. JASS has catagorized a lot of things as objects in it's language, such as effects, widgets, unit HP and mana, and booleans. It then manipulates said objects through it's coding.
It may also benefit you to know scripts & scripting (Which is what JASS is) are a little different from pure programming. Typically Game Designers use scripts and scripting languages to create cool spell effects or events in games.
However, the Software engineers use powerful programming languages like C++ to create scripting systems like JASS. For example, Ruby is used to create RGSS, or Ruby Game Scripting System.
A simple example of a game creation team may be conveyed like this:
Vexorian is a Software Engineer who creates the Game Engine
ShamanYourAnus is a Modeler and Texturer who creates the models, special effects, and art
Icefrog is a Game Designer who uses the scripting languages, the World Editor, and the models to create a game