---
url: /api/core/types/utils/type-to-map-identity-cb.md
description: api documentation of ToMapIdentityCB from @tsed/core
---

## Usage

```typescript
import { ToMapIdentityCB } from "@tsed/core/src/utils/toMap";
```

> See [/packages/core/src/utils/toMap.ts](https://github.com/tsedio/tsed/blob/v8.37.1/packages/core/src/utils/toMap.ts#L0-L0).

## Overview

```ts
type ToMapIdentityCB<V> = (item: V, index: string | number) => string | string[];
```

## Description

Callback function type for generating map keys from items.