[Home](./index.md) > [@firebase/database](./database.md) > [onChildRemoved](./database.onchildremoved_1.md) ## onChildRemoved() function Listens for data changes at a particular location. This is the primary way to read data from a Database. Your callback will be triggered for the initial data and again whenever the data changes. Invoke the returned unsubscribe callback to stop receiving updates. See [Retrieve Data on the Web](https://firebase.google.com/docs/database/web/retrieve-data) for more details. An `onChildRemoved` event will be triggered once every time a child is removed. The `DataSnapshot` passed into the callback will be the old data for the child that was removed. A child will get removed when either: - a client explicitly calls `remove()` on that child or one of its ancestors - a client calls `set(null)` on that child or one of its ancestors - that child has all of its children removed - there is a query in effect which now filters out the child (because it's sort order changed or the max limit was hit) Signature: ```typescript export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, options: ListenOptions): Unsubscribe; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | query | [Query](./database.query.md) | The query to run. | | callback | (snapshot: [DataSnapshot](./database.datasnapshot.md)) => unknown | A callback that fires when the specified event occurs. The callback will be passed a DataSnapshot and a string containing the key of the previous child, by sort order, or null if it is the first child. | | options | [ListenOptions](./database.listenoptions.md) | An object that can be used to configure onlyOnce, which then removes the listener after its first invocation. | Returns: [Unsubscribe](./database.unsubscribe.md) A function that can be invoked to remove the listener.