If you want to relay pricing data to the server, you instantiate ECPrice. For example, when you purchase a title via ec.purchaseTitle on ECommerceInterface, you're expected to present a price as a parameter.
ECPrice expects exactly two parameters for its single constructor: amount, and currency.
var price =newECPrice(amount, currency);
For example, let's assume you wish to instantiate a price representing 4.99 USD. Both the amount and the currency are strings.
var price =newECPrice('4.99','USD');
The amount that this ECPrice object represents, as a string. It is not converted to a numerical type for usage.
The currency this ECPrice object represents, as a string. There is no defined list of currencies checked against, so any value may be utilized.