Connection Status

useRos returns the status of the connection owned by RosProvider.

type RosConnectionStatus = "connecting" | "connected" | "closed" | "error";

const { ros, status, isConnected, error } = useRos();

Field	Description
ros	The underlying roslib.js Ros instance. Use it for low-level APIs (getTopics, etc.) not covered by a Hook.
status	The connection's current state.
isConnected	Shorthand for status === "connected".
error	The payload of the most recent error event (null if none occurred).

State transitions

connecting → connected → closed
    │            │
    └──── error ─┘

• On mount, with autoConnect (default true), status starts at "connecting".
• Once the rosbridge server accepts the connection, it becomes "connected".
• If the server disconnects, it becomes "closed". Topics/services created with reconnect_on_close re-subscribe/re-advertise automatically, but roshooks does not automatically reconnect the Ros connection itself.
• WebSocket-level errors (e.g. connection refused) set status to "error" and populate error with the event.

Example: a status badge

function ConnectionBadge() {
  const { status } = useRos();

  const color = {
    connecting: "gray",
    connected: "green",
    closed: "orange",
    error: "red",
  }[status];

  return <span style={{ color }}>{status}</span>;
}

Reconnecting with a new URL

Changing the url prop on RosProvider closes the existing connection and reconnects to the new URL.

const [url, setUrl] = useState("ws://localhost:9090");

<RosProvider url={url}>
  <App />
</RosProvider>;

If autoConnect={false}, roshooks won't connect automatically. Grab ros from useRos and call ros.connect(url) whenever you're ready (it returns a Promise<void>).