The query to run.
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.
OptionalcancelCallback: (error: Error) => unknownAn optional callback that will be notified if your
event subscription is ever canceled because your client does not have
permission to read this data (or it had permission but has now lost it).
This callback will be passed an Error object indicating why the failure
occurred.
A function that can be invoked to remove the listener.
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 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:
remove() on that child or one of its ancestorsset(null) on that child or one of its ancestorsThe query to run.
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.
An object that can be used to configure onlyOnce, which
then removes the listener after its first invocation.
A function that can be invoked to remove the listener.
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 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:
remove() on that child or one of its ancestorsset(null) on that child or one of its ancestorsThe query to run.
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.
An optional callback that will be notified if your
event subscription is ever canceled because your client does not have
permission to read this data (or it had permission but has now lost it).
This callback will be passed an Error object indicating why the failure
occurred.
An object that can be used to configure onlyOnce, which
then removes the listener after its first invocation.
A function that can be invoked to remove the listener.
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 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:
remove() on that child or one of its ancestorsset(null) on that child or one of its ancestorsThe query to run.
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.
OptionalcancelCallbackOrListenOptions: ListenOptions | ((error: Error) => unknown)Optionaloptions: ListenOptionsA function that can be invoked to remove the listener.
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 for more details.
An
onChildRemovedevent will be triggered once every time a child is removed. TheDataSnapshotpassed into the callback will be the old data for the child that was removed. A child will get removed when either:remove()on that child or one of its ancestorsset(null)on that child or one of its ancestors