js

const d1 = Temporal.Duration.from({ years: 1, months: 1 });
const d2 = Temporal.Duration.from({ years: -1, months: -1 });
const d3 = Temporal.Duration.from({ years: 1 });
const d4 = Temporal.Duration.from({ months: 12 });

console.log(d1.years); // 1
console.log(d2.years); // -1
console.log(d3.years); // 1
console.log(d4.years); // 0

// Balance d4
const d4Balanced = d4.round({
  largestUnit: "years",
  relativeTo: Temporal.PlainDate.from("2021-01-01"), // ISO 8601 calendar
});
console.log(d4Balanced.years); // 1
console.log(d4Balanced.months); // 0