I didn't actually know the answer, so I took just a few minutes to hack out my idea of how it would work and I ended up with this...
function Obj() { this.Property = null; var Constructor = function(obj) { obj.Property = "sexy"; }; Constructor(this); } var test = new Obj(); console.log(test.Property);
Basically you can see that on instantiation of the new JavaScript the internal constructor method gets executed.
I'm sure some JavaScript genius is reading this post and laughing, but fuck you...I thought it was useful!