## Apply a promotion code

Use this method to apply a promotion code that your customer enters.

This method returns a `Promise` that resolves with an object containing the following fields:
* `type`: one of either `"success"` or `"error"`
* `session`: only populated when `type` is `"success"`. Contains a [Session](/js/custom_checkout/session_object) instance representing the updated state.
* `error`: only populated when `type` is `"error"`. Contains an object with a string `message` field which can be displayed to your customer.

**Syntax:** `actions.applyPromotionCode(...)`

- `promotionCode` (string) **required**
  The promotion code to apply to the Checkout Session.

### Apply a promotion code

```jsx
actions.applyPromotionCode('PROMOTION_CODE');
```