---
title: Callbacks
description: "Callbacks stay under `callbacks` in your options, with new names:"
lastModified: "2026-10-12T12:44:54+01:00"
lastAuthor: Christopher Burns
---
## Replace callbacks

Callbacks stay under `callbacks` in your options, with new names:

|v2 callback|v3 callback|
|--|--|
|`onConsentSet`|`onPermissionsChanged` to react to what may run now. `onChoiceRecorded` to react to the visitor's accept, reject or save.|
|`onConsentChanged`|`onChoiceRecorded`. See the note below the table.|
|`onBannerFetched`|No callback. In React and Next.js, read `usePolicyResolution()` to know when the policy has resolved. In JavaScript, read `resolution` from the kernel snapshot.|
|`onError`, `onBeforeConsentRevocationReload`|Unchanged|

The `callbacks-to-v3` codemod renames `onConsentChanged` to
`onChoiceRecorded`. It leaves a `TODO(c15t v3)` comment there about the new
payload, and on `onConsentSet` and `onBannerFetched`, which it can't choose a
replacement for:

```bash
npx @c15t/cli codemods callbacks-to-v3 --dry-run --json
```

v2's `onConsentChanged` fired only when a save changed at least one category's
value, and passed `preferences` and `previousPreferences`. v3's
`onChoiceRecorded` fires for every accept, reject or save that confirms a
category, including one that saves the same values again, because each save
renews the choice's confirmation time. Its payload carries `snapshot`,
`confirmed` and `actionAt`. v3 has no callback that fires only when a save
changes a value. If you need the before and after values, use
`onPermissionsChanged`: it passes `previous` and the new `snapshot` whenever
effective permissions change, whether a save or something else changed them.

v2's `onConsentSet` also fired on initialization and hydration. In v3,
`onChoiceRecorded` runs only when the visitor acts, and `onPermissionsChanged`
runs when effective permissions change for any reason, including expiry, a
policy update or a privacy signal. Neither runs at startup if the resolved
permissions match the defaults, such as an opt-in policy that leaves every
category denied. If an external API needs the starting state, read it once at
startup as well: in React and Next.js from `useEffectivePermissions()` in an
effect, which also runs on later changes, and in JavaScript from
`kernel.events.on('init:applied', ({ snapshot }) => ...)`.

```ts title="After (v3): callbacks in your options"
callbacks: {
  onChoiceRecorded(event) {
    console.log('Visitor recorded a choice', event);
  },
  onPermissionsChanged(event) {
    console.log('Effective permissions changed', event);
  },
},
```