# Function useRecoilTransactionObserver_UNSTABLE

- useRecoilTransactionObserver_UNSTABLE(callback): void

- #### Parameters

  - callback: ((opts) => void)
    - - (opts): void

      - #### Parameters

        - opts: {
          previousSnapshot: Snapshot;
          snapshot: Snapshot;
          }

          - ##### previousSnapshot: Snapshot

          - ##### snapshot: Snapshot

        #### Returns void

  - Defined in common/temp/node_modules/.pnpm/recoil@0.7.7_react-dom@18.3.1+react@18.3.1/node_modules/recoil/index.d.ts:296