[Home](./index.md) > [@firebase/database](./database.md) > [off](./database.off.md) ## off() function Detaches a callback previously attached with `on()`. Detach a callback previously attached with `on()`. Note that if `on()` was called multiple times with the same eventType and callback, the callback will be called multiple times for each event, and `off()` must be called multiple times to remove the callback. Calling `off()` on a parent listener will not automatically remove listeners registered on child nodes, `off()` must also be called on any child listeners to remove the callback. If a callback is not specified, all callbacks for the specified eventType will be removed. Similarly, if no eventType is specified, all callbacks for the `Reference` will be removed. Individual listeners can also be removed by invoking their unsubscribe callbacks. Signature: ```typescript export declare function off(query: Query, eventType?: EventType, callback?: (snapshot: DataSnapshot, previousChildName?: string | null) => unknown): void; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | query | [Query](./database.query.md) | The query that the listener was registered with. | | eventType | [EventType](./database.eventtype.md) | One of the following strings: "value", "child\_added", "child\_changed", "child\_removed", or "child\_moved." If omitted, all callbacks for the Reference will be removed. | | callback | (snapshot: [DataSnapshot](./database.datasnapshot.md), previousChildName?: string \| null) => unknown | The callback function that was passed to on() or undefined to remove all callbacks. | Returns: void