Is it not using inheritance?

I don't even have my board yet, but when it arrives I plan to extend the DS18B20 module.

Now I'm looking at the source code at http://www.espruino.com/modules/DS18B20.js and I'm wondering if when I create multiple thermometers:

var sensor1 = require("DS18B20").connect(A1);

var sensor2 = require("DS18B20").connect(A2);

var sensor3 = require("DS18B20").connect(A13);

Is it somehow wasting memory because each object have it's own copy of getTemp() method? Or is that not the case and that's the way to do it.