# addDateDuration

> Adds times × duration to a calendar date. Years and months are applied first; when the resulting day does not exist in the target month, the month's last day is used. Weeks and days are then added. Returns undefined for a malformed date.

> **addDateDuration**(`date`, `duration`, `times?`): `string` \| `undefined`

Adds `times` × `duration` to a calendar date. Years and months are applied
first; when the resulting day does not exist in the target month, the
month's last day is used. Weeks and days are then added. Returns
`undefined` for a malformed date.

## Parameters

### date

`string`

### duration

[`DateDuration`](/utils/api/type-aliases/DateDuration)

### times?

`number` = `1`

## Returns

`string` \| `undefined`