The query to run.
A callback that fires when the specified event occurs. The callback will be passed a DataSnapshot.
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.
An onValue event will trigger once with the initial data stored at this
location, and then trigger again each time the data changes. The
DataSnapshot passed to the callback will be for the location at which
on() was called. It won't trigger until the entire contents has been
synchronized. If the location has no data, it will be triggered with an empty
DataSnapshot (val() will return null).
The query to run.
A callback that fires when the specified event occurs. The callback will be passed a DataSnapshot.
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.
An onValue event will trigger once with the initial data stored at this
location, and then trigger again each time the data changes. The
DataSnapshot passed to the callback will be for the location at which
on() was called. It won't trigger until the entire contents has been
synchronized. If the location has no data, it will be triggered with an empty
DataSnapshot (val() will return null).
The query to run.
A callback that fires when the specified event occurs. The callback will be passed a DataSnapshot.
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.
An onValue event will trigger once with the initial data stored at this
location, and then trigger again each time the data changes. The
DataSnapshot passed to the callback will be for the location at which
on() was called. It won't trigger until the entire contents has been
synchronized. If the location has no data, it will be triggered with an empty
DataSnapshot (val() will return null).
The query to run.
A callback that fires when the specified event occurs. The callback will be passed a DataSnapshot.
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.
An
onValueevent will trigger once with the initial data stored at this location, and then trigger again each time the data changes. TheDataSnapshotpassed to the callback will be for the location at whichon()was called. It won't trigger until the entire contents has been synchronized. If the location has no data, it will be triggered with an emptyDataSnapshot(val()will returnnull).