Function push

packages/database/src/api/Reference_impl.ts:599–631

(
  parent: DatabaseReference,
  value?: unknown
)

 * but can be used immediately as the `Reference` to the child location.
 */
export function push(
  parent: DatabaseReference,
  value?: unknown
): ThenableReference {
  parent = getModularInstance(parent);
  validateWritablePath('push', parent._path);
  validateFirebaseDataArg('push', value, parent._path, true);
  const now = repoServerTime(parent._repo);
  const name = nextPushId(now);

  // push() returns a ThennableReference whose promise is fulfilled with a
  // regular Reference. We use child() to create handles to two different
  // references. The first is turned into a ThennableReference below by adding
  // then() and catch() methods and is used as the return value of push(). The
  // second remains a regular Reference and is used as the fulfilled value of
  // the first ThennableReference.
  const thenablePushRef: Partial<ThenableReferenceImpl> = child(
    parent,
    name
  ) as ReferenceImpl;
  const pushRef = child(parent, name) as ReferenceImpl;

  let promise: Promise<ReferenceImpl>;
  if (value != null) {
    promise = set(pushRef, value).then(() => pushRef);
  } else {
    promise = Promise.resolve(pushRef);
  }

  thenablePushRef.then = promise.then.bind(promise);
  thenablePushRef.catch = promise.then.bind(promise, undefined);
  return thenablePushRef as ThenableReferenceImpl;
}

/**
 * Removes the data at this Database location.