> For the complete documentation index, see [llms.txt](https://developer.firmhouse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.firmhouse.com/sdks/firmhouse-sdk/reference/functions/map-extra-fields-by-field-id.md).

# mapExtraFieldsByFieldId()

```ts
mapExtraFieldsByFieldId(extraFields): Record<string, FirmhouseExtraFieldAnswer>
```

Convert a list of extra fields to a map of extra fields by field id

## Parameters

• **extraFields**: [`FirmhouseExtraFieldAnswer`](/sdks/firmhouse-sdk/reference/interfaces/firmhouse-extra-field-answer.md)\[]

List of extra fields that can be accessed from a subscription.

## Returns

`Record`<`string`, [`FirmhouseExtraFieldAnswer`](/sdks/firmhouse-sdk/reference/interfaces/firmhouse-extra-field-answer.md)>

Map of extra fields by field id