once method

JSPromise<DataSnapshot> once(
  1. String eventType, [
  2. JSFunction successCallback,
  3. JSObject? failureCallbackOrContext,
  4. JSObject? context,
])

Listens for exactly one event of the specified event type, and then stops listening.

Implementation

external JSPromise<DataSnapshot> once(
  String eventType, [
  // (a: DataSnapshot, b?: string | null) => any
  JSFunction successCallback,
  // (a: Error) => any
  JSObject? failureCallbackOrContext,
  JSObject? context,
]);