This is a more enhanced version of the WebTV box. It may well work on analogue but is really intended for deployment in a digital TV environment.

The triggering and standard HTML support is defined according to the ATVEF platform specifications which are evolving and are not yet complete but are looking to be the definitive profile that 'Browser in a box' type of system needs to conform to.

Technically, this platform is more advanced than WebTV but it is fundamentally the same.

The JavaScript capabilities in this system would be broadly in line with what you would expect a normal PC browser to cope with but there may be a few limitations here and there. There are also likely to be extensions provided as new object types and possibly some additional methods added to existing objects but these would be quite minimal.

Detecting that you are running in a set top box may not always be easy. The user agent values may not tell you that you have a DTV environment available and you may need to be a little more clever and test for the existence of specific object classes. You need to do that in a way that does not cause a run-time error of course. Its a good technique to practice to ensure your scripts run reliably regardless of whether they are designed for use with Microsoft TV or not.