Check if a date is today

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

JavaScript Version 1.0.0 · MIT · .md

function isToday({ dateTime, now }) { return new Date(dateTime).toISOString().slice(0, 10) === new Date(now).toISOString().slice(0, 10); }

Try in the local lab Download function

Input & expected output

Input

{
  "dateTime": "2026-10-28T09:00:00Z",
  "now": "2026-10-28T23:59:00Z"
}

Expected output

true

The edge case

Input

{
  "dateTime": "2026-10-28T23:30:00-03:00",
  "now": "2026-10-28T12:00:00Z"
}

Expected output

false

Know the limits

now is an input so the result is testable; pass new Date().toISOString() in your code.
“Today” is the UTC day, as in the original: a local evening can already be tomorrow, as the edge case shows.

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.

Source & maintenance

Takes the current time as an explicit input so the result is reproducible; compares UTC days as the original did. Original MDX retained as inert source evidence.

Maintained by Oveyon. Source commit: 14b481cf60df. Read the license.

Local fixture scope · Node.js 22.23.2 · reviewed October 28, 2026. No external service is required.

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.