Josh's Brain

Temporal is the new Date and Time API for Javascript.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal

• Instant: a single instant in time. ex: unix timestamp.

• Duration: a length of time, such as two hours, or the difference between two timestamps.

• PlainTime: a time of day without a date. ex: 4:30 am.

• PlainDate: a date without a time: ex: June 12, 2026

• PlainDateTime: a date and time together, but no timezone.

• ZonedDateTime: a date and time together in a specific timezone.

Create a new Instant for right now.

// simple 'now'
const now = Temporal.Now.instant();
// now with local time zone
const nowInLocalZone = Temporal.Now.zonedDateTimeISO();
// now with specific time zone
const nowInPacific = Temporal.Now.zonedDateTimeISO("America/Los_Angeles");

Difference between two Instants

const a = Temporal.Instant.from("2026-05-26T12:00:00Z");
const b = Temporal.Instant.from("2026-05-26T15:30:00Z");
const diff = a.until(b, {
  largestUnit: "hours",
  smallestUnit: "minutes"
});
console.log(diff.toString());
// "PT3H30M"
console.log(diff.hours);   // 3
console.log(diff.minutes); // 30

Difference between two PlainDates (days without time)

const start = Temporal.PlainDate.from("2026-05-01");
const end = Temporal.PlainDate.from("2026-05-26");
const diff = start.until(end);
console.log(diff.toString());
// "P25D"
console.log(diff.days);
// 25

Convert Date to Instant

// Date from String
const date = new Date("2026-05-26T12:30:00Z"); 
// Date -> Temporal.Instant
const instant = Temporal.Instant.fromEpochMilliseconds(date.getTime());
// Temporal.Instant from a string
const instantLit = Temporal.Instant.from("2026-05-26T12:30:00Z");
// Temporal.Instant -> Date
const date = new Date(instant.epochMilliseconds);

To JSON

Converting a temporal object to JSON will turn it into a plain string. ex:

const obj = {
  createdAt: Temporal.Instant.from("2026-05-26T12:30:00Z"),
  dueDate: Temporal.PlainDate.from("2026-06-01"),
  meetingTime: Temporal.PlainDateTime.from("2026-06-01T09:30:00"),
  localMeeting: Temporal.ZonedDateTime.from(
    "2026-06-01T09:30:00[America/Los_Angeles]"
  )
};

console.log(JSON.stringify(obj, null, 2));

Produces:

{
  "createdAt": "2026-05-26T12:30:00Z",
  "dueDate": "2026-06-01",
  "meetingTime": "2026-06-01T09:30:00",
  "localMeeting": "2026-06-01T09:30:00-07:00[America/Los_Angeles]"
}

From JSON

To parse JSON and get the temporal object back you'll need to preserve the type and use a custom parser.

const obj = {
  createdAt: {
    type: "Temporal.Instant",
    value: Temporal.Now.instant().toString()
  }
};

const parsed = JSON.parse(json, (key, value) => {
  if (
    value &&
    value.type === "Temporal.Instant" &&
    typeof value.value === "string"
  ) {
    return Temporal.Instant.from(value.value);
  }
  return value;
});

asd