A Node.js application written in ESM uses CommonJS distribution of the SDK

Is your feature request related to a problem? Please describe.

A Node.js application written in ESM uses CommonJS distribution of the SDK.

Example code:

// index.mjs
import { DynamoDB } from "@aws-sdk/client-dynamodb";

const client = new DynamoDB({});
await client.listTables({});

• In VSCode, add a breakpoint on the line which calls listTables.
• Click on “Run and Debug” in the Debugging View to start debugging.
• The debug session will break at listTables.
• Click on “Step Into” debug action.
• Note that debug session steps into node_modules/@aws-sdk/property-provider/dist-cjs/chain.js

It uses distribution in dist-cjs and not in dist-es

Screen recording

https://user-images.githubusercontent.com/16024985/137387077-75425c67-ccc1-43e9-a025-7786b248116d.mov

Describe the solution you’d like

The Node.js application written in ESM should use distribution in dist-es The Node.js application written in ESM should use folder in dist-node-esm (UPDATE April 2022)

Describe alternatives you’ve considered

A different distribution for Node.js ESM, which can be take up while implementing Node.js specific distributions in https://github.com/aws/aws-sdk-js-v3/issues/2889 to avoid increasing install size.

Additional context

• Debugging in VSCode https://code.visualstudio.com/docs/editor/debugging
• Conditional Exports in Node.js https://nodejs.org/api/packages.html#packages_conditional_exports

[simonbuchan]

This one should actually be pretty easy to fix, assuming es doesn’t assume browser: the current package.json files have:

  "main": "./dist-cjs/index.js",
  "module": "./dist-es/index.js",

which was the bundler convention, but the native Node ESM support ignores module, and instead uses the new exports specification, and in particular conditional exports, so simply adding the following should work:

  "exports": {
    "require": "./dist-cjs/index.js",
    "import": "./dist-es/index.js",
  },

Note that this will enforce encapsulation, so anybody doing something like import "@aws-sdk/client-s3/lib/some-file.js" will be broken… but you probably want that.

[github-actions[bot]]

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