---
title: Callbacks
description: Run code in a Nuxt app when a visitor records a consent choice,
  when permissions change, before a revocation reload, and when c15t reports an
  error.
group: frameworks
lastModified: "2026-10-10T16:01:45+01:00"
---
## Register callbacks

Callbacks are functions, so they go under the `c15t` key of
`app/app.config.ts`, not in `nuxt.config.ts`. Module options reach the
browser as JSON, which drops functions. Keep the callbacks in their own file:

```ts title="app/consent-callbacks.ts"
import type { C15tNuxtConfig } from 'c15t/vue';

export const callbacks = {
	// The visitor clicked Accept all, Reject all or Save.
	onChoiceRecorded: ({ snapshot }) => {
		console.info('Choice recorded', snapshot.explicitChoice);
	},
	onError: ({ error }) => {
		console.error('c15t', error);
	},
	// Permissions changed for any reason: a choice, an expired choice, a new
	// policy or a privacy signal.
	onPermissionsChanged: ({ previous, snapshot }) => {
		console.info('Permissions', previous, snapshot.effectivePermissions);
	},
} satisfies NonNullable<C15tNuxtConfig['callbacks']>;
```

Then add them next to `scripts` in `app/app.config.ts`:

```ts title="app/app.config.ts"
export default defineAppConfig({ c15t: { callbacks, scripts } });
```

The module wires the callbacks once when its plugin runs. Visitor actions
happen in the browser, so that is where these callbacks run.

## Available callbacks

|Callback|Runs when|Receives|
|--|--|--|
|`onChoiceRecorded`|The visitor clicks Accept All, Reject All or Save Settings, in the stock UI or through `useConsentSave()`.|`snapshot`, `confirmed` (the categories the action covered) and `actionAt`|
|`onPermissionsChanged`|Any effective permission changes value.|`snapshot` and `previous`, the permissions before the change|
|`onBeforeConsentRevocationReload`|A save withdraws a granted category or vendor, right before c15t reloads the page.|`preferences`, the permissions after the save|
|`onError`|A consent command fails, for example a save the backend rejects.|`error`, a message string|

## onChoiceRecorded or onPermissionsChanged

`onChoiceRecorded` fires only for a visitor's action. Use it to count consent
decisions or to send the choice to your own analytics.

`onPermissionsChanged` also fires when a stored choice expires, when a new
policy applies, and when a privacy signal such as Global Privacy Control
changes, with no action from the visitor. Use it to start or stop code that
depends on a permission. Do not treat it as evidence that the visitor chose
anything.

Dismissing a notice fires neither callback, because it records no choice and
changes no permission. Subscribe to it with
`useConsentKernel().events.on('notice:dismissed', listener)`.
[How consent works](/docs/concepts/how-consent-works#a-permission-is-not-a-recorded-choice)
explains the difference.

## Before a revocation reload

Removing a script tag cannot stop code that already ran, so c15t reloads the
page after a save withdraws a granted category or vendor.
`onBeforeConsentRevocationReload` runs synchronously right before that. Use
it to call a vendor's shutdown API. Avoid long work, because the reload does
not wait. Set `reloadOnConsentRevoked: false` to handle revocation yourself.

## Verify

Open the console, load a page and click **Accept All**. `onChoiceRecorded` logs
once and `onPermissionsChanged` logs the new permissions. Reload: neither logs
a new choice. Withdraw a category in preferences and save, and the
revocation callback runs before the page reloads.