import jetSet from 'jet-set';

let fruitBasket = jetSet({
  apples: 3,
  oranges: 5,
  bananas: 6,
});

fruitBasket.limes = 4;
fruitBasket.lemons = 2;

// no big deal so far? let's add a derived/dynamic property
fruitBasket.totalFruit = () => {
  let sum = 0;

  for (let fruit in fruitBasket) {
    sum += fruitBasket[fruit];
  }

  return sum;
};

console.log(fruitBasket.totalFruit); // 20

// watch for changes, even on dynamic properties
const buyMoreCitrus = () => {
  const { oranges, limes, lemons } = fruitBasket;

  if (oranges < 2 || limes < 2 || lemons < 2) {
    console.log('Buy more citrus!');
  }
};

fruitBasket.onChange('totalFruit', buyMoreCitrus);

fruitBasket.lemons = 1; // > "Buy more citrus!"