> 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/event_disconnecting.md).

# 4.3.27 event\_disconnecting

* `reason` (String) 断开连接的原因（客户端或服务器端）

当客户端将要断开连接（但尚未离开其`房间`）时触发。

```javascript
io.on('connection',socket=>{
    socket.on('disconnecting',reason=>{
        let rooms= Object.keys(socket.rooms)
    })
})
```

这些是保留的事件（连同`connect`、`newlistener`和`removelistener`），不能用作事件名称。