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.
An onChildAdded event will be triggered once for each initial child at this
location, and it will be triggered again every time a new child is added. The
DataSnapshot passed into the callback will reflect the data for the
relevant child. For ordering purposes, it is passed a second argument which
is a string containing the key of the previous sibling child by sort order,
or null if it is the first child.
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.
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 onChildAdded event will be triggered once for each initial child at this
location, and it will be triggered again every time a new child is added. The
DataSnapshot passed into the callback will reflect the data for the
relevant child. For ordering purposes, it is passed a second argument which
is a string containing the key of the previous sibling child by sort order,
or null if it is the first child.
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.
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 onChildAdded event will be triggered once for each initial child at this
location, and it will be triggered again every time a new child is added. The
DataSnapshot passed into the callback will reflect the data for the
relevant child. For ordering purposes, it is passed a second argument which
is a string containing the key of the previous sibling child by sort order,
or null if it is the first child.
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.
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
onChildAddedevent will be triggered once for each initial child at this location, and it will be triggered again every time a new child is added. TheDataSnapshotpassed into the callback will reflect the data for the relevant child. For ordering purposes, it is passed a second argument which is a string containing the key of the previous sibling child by sort order, ornullif it is the first child.