---
lang: en
title: 'API docs: core.extensionpoint'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/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.

**Signature:**

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

## Parameters

<table><thead><tr><th>

Parameter


</th><th>

Type


</th><th>

Description


</th></tr></thead>
<tbody><tr><td markdown="1">

name


</td><td markdown="1">

string


</td><td markdown="1">

Name of the extension point


</td></tr>
<tr><td markdown="1">

specs


</td><td markdown="1">

[BindingSpec](./context.bindingspec.md)<!-- -->\[\]


</td><td markdown="1">


</td></tr>
</tbody></table>

**Returns:**

ClassDecorator

## Example


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

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