# Subscribe for Notifications

<figure><img src="/files/bIzQEoHHnl2MuTZNneEC" alt=""><figcaption></figcaption></figure>

Notifications make it easy for your controller to always know the current state of the titles that it manages.

To implement, use the [`scheduleCommand`](/captivate-api/javascript-api-reference/using-the-servicehandler/schedulecommand-method.md) API call.

`scheduleCommand` is a general purpose API that supports a wide range of commands. In fact, even the `scheduleAction` call can be made through `scheduleCommand`.

It takes three parameters: the command name, a JavaScript object with all the parameters, and a JavaScript object with optional variable settings. Note that the last app in the tour, [JSON Command Tester](/api-examples/json-command-tester.md), provides a way to try all the commands and it documents all of the parameters for each.

```javascript
scheduler.scheduleCommand('subscribe', { input: inputName, events: 'play, data' }, {});
```

In this case, the command is “subscribe.” The parameter “input” instructs it to subscribe to all titles connected to this input, and the parameter “events” sets which behaviors to notify: “play” for playback status and “data” for changes in variables.

To receive notifications, you must also respond to [`onNotify`](/captivate-api/javascript-api-reference/using-the-servicehandler/signals.md) events from the scheduler.

```javascript
// Once subcriptions are enabled, listen for onNotify callbacks.
scheduler.onNotify.connect((notification) => {
  // Convert the payload string into a JavaScript object.
  let jsonReply = JSON.parse(notification);
  // And then use the object to inform the state...
});
```

\\


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