---
lang: en
title: 'API docs: core.extensions'
keywords: LoopBack 4.0, LoopBack 4
sidebar: lb4_sidebar
permalink: /doc/en/lb4/apidocs.core.extensions.html
---

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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [extensions](./core.extensions.md)

## extensions() function

Shortcut to inject extensions for the given extension point.

<b>Signature:</b>

```typescript
export declare function extensions(extensionPointName?: string): (target: Object, member: string, methodDescriptorOrParameterIndex?: number | TypedPropertyDescriptor<any> | undefined) => void;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  extensionPointName | <code>string</code> | Name of the extension point. If not supplied, we use the <code>name</code> tag from the extension point binding or the class name of the extension point class. If a class needs to inject extensions from multiple extension points, use different <code>extensionPointName</code> for different types of extensions. |

<b>Returns:</b>

`(target: Object, member: string, methodDescriptorOrParameterIndex?: number | TypedPropertyDescriptor<any> | undefined) => void`

## Example


```ts
import {Getter} from '@loopback/context';
import {extensionPoint, extensions} from '@loopback/core';

@extensionPoint(GREETER_EXTENSION_POINT_NAME)
export class GreetingService {
 constructor(
   @extensions() // Inject extensions for the extension point
   private getGreeters: Getter<Greeter[]>,
   // ...
) {
  // ...
}

```