How to use VB API (actually COM) in JavaScript ?

I found few JavaScript examples, one shown below and it works fine on Windows HTA script (JavaScript). 

VBA

Set cAC = New CCpfcAsyncConnection ' VBA

JavaScript

// equivalant to the line above but in JavaScript
cAC = new ActiveXObject("pfcls.pfcAsyncConnection") // this line works fine

But I can't find other equivalent statements in JavaScript like this:  
VBA

Set Mitem = New CMpfcModelItem

JavaScript

Mitem = what? // don't know how to do this in JavaScript

Also this example: 
VBA

Dim type as EpfcFeatureType
type = EpfcFeatureType.EpfcFEATTYPE_HOLE

JavaScript

what's the equivalent statement in javascript?