## isDayOfWeek() function

**Signature:**

```typescript
export declare function isDayOfWeek(value: string | undefined): value is DayOfWeek;
```

## Parameters

| Parameter | Type | Description |
| --- | --- | --- |
| value | string \| undefined |  |

**Returns:**

value is [DayOfWeek](/content/docs/sdk/core.dayofweek)