SebastianVerified account

If you use a build tool that includes type checking along with bundling (e.g. webpack + ts-loader without transpileOnly, create-react-app), do you do so only on build or also during development? Why not just run tsc/flow as a separate build step in CI, and in your IDE for dev?

The bundler is typically the second thing, after their editor, that gives a developer insight to the validity of their code. For that reason it makes a lot of sense to consider the bundler as your development environment. For production it doesn't really make any sense.

i.e see errors in both editor AND terminal/browser console? But maybe not block the build so you can hack and fix errors later? Seems duplicative to me... I would have thought people wanted it the other way: block build in production for linter/type errors.

People who want it to block production builds will just run their lint command before. Not everyone has their editor configured correctly for a project, errors may not necessarily be shown, it's an additional way before their changes hit CI and they release they needed to run X.