aws-sdk-js-v3-usage

Do not use emojis in any code, comments, or output when this skill is active.

AWS SDK for JavaScript v3

Package Structure

• @aws-sdk/client-* — one per service, generated by smithy-typescript; one-to-one with AWS services and operations
• @aws-sdk/lib-* — higher-level helpers (e.g. lib-dynamodb, lib-storage)
• @aws-sdk/* (no prefix) — utility packages (mostly internal; don't import deep paths)

Always import from the package root:

import { S3Client } from "@aws-sdk/client-s3"; // correct
// NOT: import { S3Client } from "@aws-sdk/client-s3/dist-cjs/S3Client"

Two Client Styles

Bare-bones (preferred — smaller bundle):

import { S3Client, GetObjectCommand } from "@aws-sdk/client-s3";
const client = new S3Client({ region: "us-east-1" });
const output = await client.send(new GetObjectCommand({ Bucket: "b", Key: "k" }));

Aggregated (v2-style but NOT v2, larger bundle):

import { S3 } from "@aws-sdk/client-s3";
const client = new S3({ region: "us-east-1" });
const output = await client.getObject({ Bucket: "b", Key: "k" });

Client Configuration

No global config in v3 — pass config to each client. region is always required; set it explicitly or via AWS_REGION env var.

const config = { region: "us-east-1", maxAttempts: 5 };
const s3 = new S3Client(config);
const dynamo = new DynamoDBClient(config);

Do not read or mutate client.config after instantiation — it is a resolved form (e.g. region becomes an async function). See references/effective-practices.md.

For HTTP handler (NodeHttpHandler from @smithy/node-http-handler), retry strategy, endpoint details, logging, FIPS, dual-stack, protocol selection, and S3-specific options → see references/clients.md.

Credentials

All providers from @aws-sdk/credential-providers. Credentials are lazy and cached per client until ~5 min before expiry.

// Default chain (env → ini → IMDS/ECS) — use in most Node.js apps
const client = new S3Client({ credentials: fromNodeProviderChain() });

// Assume role (NOTE: fromTemporaryCredentials is correct for STS AssumeRole)
const client = new S3Client({
  credentials: fromTemporaryCredentials({ params: { RoleArn: "arn:aws:iam::123456789012:role/MyRole" } }),
});

// Named profile
const client = new S3Client({ profile: "my-profile" });