> For the complete documentation index, see [llms.txt](https://socket.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://socket.gitbook.io/docs/4-fu-wu-duan-apiserverapi/4.3-socket/socket_join_room_callback.md).

# 4.3.15 socket\_join\_room\_callback

* `room` (String)
* `callback`(Function)
* **Returns** 连接的`Socket`

将客户端添加到`room`中，并根据需要触发带有`err`签名（如果有）的回调。

```javascript
i.on('connection',(socket)=>{
    socket.join('room 237',()=>{
        let rooms= Object.keys(socket.room);
        console.log(rooms); // [ <socket.id>, 'room 237' ]
        io.to("room 237").emit('a new ueser has joined the room'); // 广播给房间里的每个人
    })
})
```

连接室的机制由已配置的`Adapter`（参见上面的 `Server#adapter`）处理，默认为[socket.io-adapter](https://github.com/socketio/socket.io-adapter)。

为了您的方便，每个socket自动连接由其ID标识的房间（请参见`Socket#id`）。这使得向其他socket广播消息变得容易：

```javascript
io.on('connection',(socket)=>{
    socket.on('say to someone',(id,msg)=>{
        // 使用给定的ID向socket发送私有消息
        socket.to(id).emit("my message",msg)
    })
})
```


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