Why do we need "build": "tsc" and "watch": "tsc -w"

[ghdoergeloh]

I was wondering why there are these scripts to compile typescript files. As far as I can see, no action in a cdk app needs the .js or .d.ts files.
"app": "npx ts-node --prefer-ts-exts bin/hello-cdk.ts" should do everything to synth, deploy or do anything else with the app.
Even ts-jest can work with ts files without compiling them.
Compiling the files can even cause some errors when testing so I had to add some options to the default jest.config.js to prevent duplicate mocks and prefer the ts files, especially when compiled ones are outdated:

const { defaults } = require('jest-config');

module.exports = {
...
  modulePathIgnorePatterns: ['.*__mocks__.*\\.(js|jsx)$'],
  moduleFileExtensions: ['ts', 'tsx', ...defaults.moduleFileExtensions],
...
};

But the cdkworkshop still says that we need to compile the ts files https://cdkworkshop.com/20-typescript/20-create-project/200-watch.html

The only case I can imagine, is when publishing a construct as a npm package, while a npm package should contain the compiled files.
Is there any other case that I am missing?

[skinny85]

I think the "build" and "watch" scripts generated by default in the package.json files by the cdk init command are historic artifacts. The switch to TS-Node was actually an external contribution, and I think we missed removing them (from package.json, and also from the CDK Workshop).

[peterwoodworth]

I wonder how many users use this, I know I used to run watch for a while when I started because that's what workshop suggested, which was my intro to CDK.

What do you think about removing this from the workshop @skinny85?

[skinny85]

I think it's fine to remove that part from the workshop, will make it a little simpler.

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.