The CJS build of Vite's Node API is deprecated

[EvgenyOrekhov]

Started getting this error every time I run knip:

The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-dep

I use:

• knip 2.41.3
• Vitest 0.34.6
• Node.js 18.18.2

[webpro]

Is it just a warning, or an error? How can I reproduce it?

[EvgenyOrekhov]

It's just a warning. I assume you need to install the latest version of vitest and add some basic vitest.config.ts.

[EvgenyOrekhov]

Steps to reproduce:

mkdir knip-vitest
cd knip-vitest
npm i -D vitest knip

Then create file vitest.config.ts

/// <reference types="vitest" />
import { defineConfig } from 'vitest/config';
export default defineConfig({});

Then run npx knip > result.txt, and you should see the warning.

Note: you have to run npx knip > result.txt, and not just npx knip to see the warning, because npx knip clears the current output line.

[webpro]

Thanks, gotcha.

The first thing that caught my eye is that you probably want to set "type": "module" in package.json, to nudge Node.js and other module resolvers in the right direction.

However, that won't be sufficient today, I think there's an issue in jiti. Knip uses jiti under the hood to load such config files. Hacked around a bit and didn't get it to work (not even when using the .mts extension), maybe fixed when they make the switch to ESM being the native import/loading mechanism in jiti v2.

To get rid of the warning today, you could switch to use the .mjs extension.

Note: you have to run npx knip > result.txt, and not just npx knip to see the warning, because npx knip clears the current output line.

Knip should not clear or overwrite that output (e.g. it does not do that on my macOS with Bash). Can I ask which shell you are using?

You can use --no-progress or -n so Knip won't rewrite lines or clear stdout.

[EvgenyOrekhov]

Knip should not clear or overwrite that output (e.g. it does not do that on my macOS with Bash). Can I ask which shell you are using?

I use zsh on my macOS. I can see the warning gets shown for a split second. With --no-progress it stays on the screen.
BTW I believe the warning goes to stderr, not stdout.

[yekver]

I have the same issue with '--no-progress' flag provided. In package.json set "type": "module".

[webpro]

@yekver Those are two different things. The real issue here is about CJS vs ESM (with "type": "module").

The other thing is only about how Knip logs things to stdout (and stderr), and there seems to be a difference between Bash and Zsh. That's why we discuss the --no-progress flag.

[JoshuaKGoldberg]

FWIW I see the CJS notice in JoshuaKGoldberg/create-typescript-app#1082.

joshgoldberg ~/repos/create-typescript-app $ pnpm lint:knip

> [email protected] lint:knip /Users/josh/repos/create-typescript-app
> knip

Analyzing workspace ....
The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-deprecated
✂️  Excellent, Knip found no issues.
joshgoldberg ~/repos/create-typescript-app $ 

[webpro]

Yeah, it's coming from jiti, waiting for them to go fully ESM :)

[webpro]

See #565