Check if a date occurs in the current year

Compare the UTC year of a date-time with the current one.

JavaScript Version 1.0.0 · MIT · .md

function isCurrentYear({ dateTime, now }) { return new Date(dateTime).getUTCFullYear() === new Date(now).getUTCFullYear(); }

Input & expected output

{
  "dateTime": "2026-01-15T00:00:00Z",
  "now": "2026-10-28T12:00:00Z"
}

true

The edge case

{
  "dateTime": "2025-12-31T23:00:00-03:00",
  "now": "2026-10-28T12:00:00Z"
}

true

Know the limits

• The year is the UTC year: New Year’s Eve at 23:00 in São Paulo is already 2026 in UTC, as the edge case shows.
• now is an input so the result is testable.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Check whether all values are equal — Compare every item with the first using Object.is.
• Check whether an object is empty — Check for own enumerable string keys on a JSON object.
• Check whether an integer is even — Test parity for safe integers, including zero and negative values.