## mapByIdentifier() function

Returns a Map of resources from a bundle, using the specified identifier system as the key.

**Signature:**

```typescript
export declare function mapByIdentifier<T extends Resource = Resource>(resourceBundle: Bundle<T>, identifierSystem: string): Map<string, T>;
```

## Parameters

| Parameter          | Type               | Description                                           |
| ------------------ | ------------------ | ----------------------------------------------------- |
| resourceBundle     | Bundle<T>          | The bundle of resources.                              |
| identifierSystem   | string             | The identifier system to use for keys.               |

**Returns:**

Map<string, T>

Map of resources keyed by identifier value for the specified system.