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