voluptasmollitia/docs-exp/database.off.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/database](./database.md) &gt; [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.

<b>Signature:</b>

```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 <code>Reference</code> will be removed. |
|  callback | (snapshot: [DataSnapshot](./database.datasnapshot.md)<!-- -->, previousChildName?: string \| null) =&gt; unknown | The callback function that was passed to <code>on()</code> or <code>undefined</code> to remove all callbacks. |

<b>Returns:</b>

void