Use ESModules in notes app backend

[trivikr]

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

Not a problem, but it would be good to show Node.js using ESM as:

• Node.js 10.x is the last LTS version not supporting ESM, and it's going end-of-life on April 30th, 2021.
• JavaScript package maintainers are excited about dropping support for commonjs format. Example blog post: https://blog.sindresorhus.com/get-ready-for-esm-aa53530b3f77

ESM comes with many benefits, like language-level syntax, browser support, defaults to strict mode, async loading, top-level await, improved static analysis & tree-shaking, and more.

• Overview on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
• Node.js docs on ESM: https://nodejs.org/api/esm.html

Describe the solution you'd like

Use ESM modules in the todo app backend by setting "type": "module" in package.json. Docs: https://nodejs.org/api/esm.html#esm_enabling

Describe alternatives you've considered

Sticking with using commonjs for the backend.

[trivikr]

Experimental commits can be viewed in https://github.com/trivikr/aws-sdk-js-notes-app/commits/use-esm

Not going ahead right now as:

• Webpack doesn't yet support output.libraryTarget: 'module' https://github.com/webpack/webpack/issues/2933
• minor: ESM support is experimental in ts-node https://github.com/TypeStrong/ts-node/issues/1007
• minor: webpack doesn't support ES6 config file https://stackoverflow.com/a/65882354

[cspotcode]

You probably know this, but just to clarify, ts-node's ESM support is experimental out of necessity, because node's ESM loader hooks are experimental. So there's no way we can guarantee a stable feature built on unstable node APIs.

Even though node's ESM feature is "stable," the reality is that it's still limited compared to CommonJS, due to the unstable nature of ESM loader hooks.

[trivikr]

No longer needed, as we now bundle through aws_cdk.aws_lambda_nodejs https://github.com/aws-samples/aws-sdk-js-notes-app/pull/122