Check if a date is a weekday

Return true for a YYYY-MM-DD date from Monday to Friday.

JavaScript Version 1.0.0 · MIT · .md

function isWeekday(date) { return new Date(date).getUTCDay() % 6 !== 0; }

Input & expected output

"2026-10-28"

true

The edge case

"2026-11-01"

false

Know the limits

• Reads the UTC calendar day; the original used local time on a Date object. Public holidays are not considered.

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.