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docs: add warning regarding using socket.data reference equality #436

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61c6c95
docs: add warning regarding using socket.data reference equality
nedgrady Jan 31, 2024
33606ac
Fix typo
nedgrady Feb 1, 2024
97687a7
Remove bad 'good' example.
nedgrady Feb 2, 2024
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18 changes: 18 additions & 0 deletions docs/categories/02-Server/server-socket-instance.md
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Expand Up @@ -140,6 +140,24 @@ console.log(sockets[0].data.username); // "alice"

More information [here](server-instance.md#utility-methods).

:::caution
Do not rely on reference equality when using properties of `data`.
:::

```js
// BAD
const activeUsers = new Set();
io.on("connection", (socket) => {
socket.data.user = { name: "alice" };
activeUsers.add(socket.data.user);

socket.on("disconnect", () => {
// Socket.IO makes no guarantee data.user will reference the same object...
activeUsers.delete(socket.data.user);
});
});
```

## Socket#conn

A reference to the underlying Engine.IO socket (see [here](../01-Documentation/how-it-works.md)).
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