flatThen
abstract external fun <R : JsAny?> flatThen(onFulfilled: (T) -> PromiseResult<R>): PromiseLike<R>(source)
abstract external fun <R : JsAny?> flatThen(onFulfilled: (T) -> PromiseResult<R>, onRejected: (JsErrorLike?) -> PromiseResult<R>): PromiseLike<R>(source)