@loopback/docs/site/apidocs/socketio.socketioserver.use.md

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---
lang: en
title: 'API docs: socketio.socketioserver.use'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/extensions/socketio
permalink: /doc/en/lb4/apidocs.socketio.socketioserver.use.html
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[Home](./index.md) &gt; [@loopback/socketio](./socketio.md) &gt; [SocketIoServer](./socketio.socketioserver.md) &gt; [use](./socketio.socketioserver.use.md)

## SocketIoServer.use() method

Register a sock.io middleware function

**Signature:**

```typescript
use(fn: SockIOMiddleware): Server<import("socket.io").DefaultEventsMap, import("socket.io").DefaultEventsMap, import("socket.io").DefaultEventsMap, any>;
```

## Parameters

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

Parameter


</th><th>

Type


</th><th>

Description


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

fn


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

[SockIOMiddleware](./socketio.sockiomiddleware.md)


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


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

**Returns:**

Server&lt;import("socket.io").DefaultEventsMap, import("socket.io").DefaultEventsMap, import("socket.io").DefaultEventsMap, any&gt;