---
lang: en
title: 'API docs: core.extensionpoint'
keywords: LoopBack 4.0, LoopBack 4
sidebar: lb4_sidebar
editurl: https://github.com/strongloop/loopback-next/tree/master/packages/core
permalink: /doc/en/lb4/apidocs.core.extensionpoint.html
---

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

## extensionPoint() function

Decorate a class as a named extension point. If the decoration is not present, the name of the class will be used.

<b>Signature:</b>

```typescript
export declare function extensionPoint(name: string, ...specs: BindingSpec[]): ClassDecorator;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  name | <code>string</code> | Name of the extension point |
|  specs | <code>BindingSpec[]</code> |  |

<b>Returns:</b>

`ClassDecorator`

## Example


```ts
import {extensionPoint} from '@loopback/core';

@extensionPoint(GREETER_EXTENSION_POINT_NAME)
export class GreetingService {
  // ...
}

```


