As of the last commit all Joose tests pass under JScript .NET.
What is not so nice is that JScript .NET wants to report an error to Microsoft every time you deference a non-existant property as a function. Oh, well.
Another interesting thing is that JScript .NET actually passes more tests than JScript. There is one unofficial feature in Joose that allows un-applying of roles which contain only method modifiers (yes, a plugin system on steroids!) at runtime. I haven't found a way to make this work under JScript, because it can only (easily) made to work with the __proto__ property which enables exchanging the prototype of a single object at runtime. Well, under JScript .NET there is no __proto__ property, but it still works. There must be something else going on in the background. Joose is also switching object.contructor to a new value and maybe .NET is using that path to find the object's prototype property?