/aws-sdk-js-v3-usage

TypeScript Reference

Remove | undefined from Response Structures

SDK response fields are typed as T | undefined by default. To opt out of this for a client:

import { S3Client } from "@aws-sdk/client-s3";
import type { AssertiveClient } from "@smithy/types";

const client = new S3Client({}) as AssertiveClient<S3Client>;
// Response fields are no longer unioned with undefined

See @smithy/types docs for AssertiveClient and UncheckedClient (skips all runtime checks).

Narrow Streaming Blob Types

GetObjectCommand Body is typed as a union because the runtime type depends on the request handler (Node.js vs browser). To narrow it:

import { S3Client } from "@aws-sdk/client-s3";
import type { NodeJsClient } from "@smithy/types";

const client = new NodeJsClient<S3Client>(new S3Client({}));
// Body is now typed as NodeJsRuntimeStreamingBlob (Readable) instead of a union

Minimum TypeScript Version

No official minimum. Use a recent version. The SDK's own TypeScript version is in the root package.json of the aws-sdk-js-v3 repo.