# Check if a date is a weekday

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

Canonical: https://1loc.dev/validator/check-if-a-date-is-a-weekday/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

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

## Input

```json
"2026-10-28"
```

## Expected output

```json
true
```

## Edge case

Input:
```json
"2026-11-01"
```
Output:
```json
false
```

## Limits

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

The lab validates types and size before calling this function. Add equivalent validation at your own trust boundary.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/check-if-a-date-is-a-weekday.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: See original repository history
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Reads a validated YYYY-MM-DD date in UTC instead of a local Date object. Original MDX retained as inert source evidence.