effector_demo.js

const bills = createStore([{id: 0, state: 0}, {id: 1, state: 2}]);
const selected = createStore(0);

const cheatersStore = createStoreObject({
	bills,
  selected
})

const validate = createEvent('validate')
bills.on(validate, (bills, idBill) => {
  const idx = bills.findIndex(bill => bill.id === idBill);
  bills[idx].state = 1;
  return bills;
});

const reject = createEvent('reject')
bills.on(reject, (bills, idBill) => {
  const idx = bills.findIndex(bill => bill.id === idBill);
  bills[idx].state = 2;
  return bills;
});

const selectBill = createEvent("select bill");
selected.on(selectBill, (previous, newSelected) => newSelected);
selected.on(validate, (previous, idBill) => previous + 1);

validate(1);
reject(0);
selectBill(20);
validate(1);
bills.watch(console.log);
selected.watch(console.log);