Class

First thing first, classes require to be registered before used in Nucleoid:

class Order {
  constructor(item, qty) {
    this.item = item;
    this.qty = qty;
  }
}

nucleoid.register(Order);

Objects

The same thing for objects, once initiated and assigned to the var variable as well as it stored.

app.post("/orders", () => {
  var order = new Order("ITEM-123", 3);
  return order;
});

and it can retrieve by its var variable as mentioned earlier.

app.get("/orders", () => {
  return order;
});

{
  "id": "order0",
  "item": "ITEM-123",
  "qty": 1
}

if object initiated without assigning var variable, the runtime automatically assign var variable along with id

app.post("/test", () => new Order("ITEM-123", 3));

{
  "id": "order0",
  "item": "ITEM-123",
  "qty": 1
}

💡 id of object is always the same to its global var so that either can be used to retrieve the object like
Order["order0"] and order0.

if object assigned to either let or const, the runtime will create var variable the same as its id

app.post("/orders", () => {
  const order = new Order("ITEM-123", 3);
  return order;
});

{
  "id": "order1",
  "item": "ITEM-123",
  "qty": 1
}

Now, it can use its id as var in order to retrieve the object

app.get("/test", () => order1);