updateFieldPath method
Updates fields in the document referred to by this DocumentReference.
The update will fail if applied to a document that does not exist.
Nested fields can be updated by providing dot-separated field path strings or by providing FieldPath objects.
A Precondition restricting this update can be specified as the last
argument.
@param field The first field to update.
@param value The first value.
@param moreFieldsOrPrecondition An alternating list of field paths and
values to update, optionally followed by a Precondition to enforce on
this update.
@throws Error If the provided input is not valid Firestore data.
@return A Promise resolved with the write time of this update.
Implementation
@JS('update')
external JSPromise<WriteResult> updateFieldPath(
JSAny field,
JSObject value, [
JSArray<JSAny> precondition,
]);