Get the weekday of a date

Look up the English weekday name of a date.

JavaScript Version 1.0.0 · MIT · .md

function weekday(date) { return ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'][new Date(date).getUTCDay()]; }

Try in the local lab Download function

Input & expected output

Input

"2026-10-28"

Expected output

"Wednesday"

The edge case

Input

"2026-11-01"

Expected output

"Sunday"

Know the limits

English only; Intl.DateTimeFormat with { weekday: "long" } localizes it.

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

Reads the UTC weekday. 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

Compare two dates — Compare validated ISO calendar dates in UTC and return -1, 0 or 1.
Add AM PM suffix to an hour — Turn an hour from 0 to 23 into a 12-hour label with am or pm.
Calculate the number of days between two dates — Count whole calendar days between two YYYY-MM-DD dates.