Export Typescript types declaration

[Kapcash]

This plugin, when imported from a .ts file, throws types error because it doesn't declare any types.

I think it would be a good enhancement to declare at single a single types.d.ts in the package to export types, without converting the whole source code to Typescript.
This way, Typescript users can seamlessly import the package without having to declare themselves the types :)

You can even export declaration types from .js files! https://www.typescriptlang.org/docs/handbook/declaration-files/dts-from-js.html

[Kapcash]

Here is my own, primitive, declaration file for this package:

packages.d.ts

declare module 'eslint-plugin-cypress/flat' {
  import type { ESLint } from 'eslint';
  const plugin: ESLint.Plugin;

  export default plugin;
};

[MikeMcC399]

@Kapcash

Thank you for raising this issue!

According to the ESLint v9 documentation TypeScript Configuration Files

This feature is currently experimental and may change in future versions.

Please check the above documentation link and see if it is helpful for you.

[nbouvrette]

@MikeMcC399 ESLint officially support eslint.config.ts since January 2025.

Like @Kapcash, I had to do a similar workaround and create my own type declaration:

declare module 'eslint-plugin-cypress/flat' {
  import type { Linter } from 'eslint'

  const plugin: {
    configs: {
      recommended: Linter.Config
      [key: string]: Linter.Config | undefined
    }
  }

  export default plugin
}

Ideally this should be shipped with this package to avoid these workarounds.

[MikeMcC399]

@nbouvrette

Thank you very much for highlighting the transition of TypeScript configuration files from an experimental feature to stable support by ESLint! This occurred with ESLint 9.18.0 released on Jan 10, 2025.

Given the change to stable support by ESLint it would definitely make sense to add this capability to the plugin.

The barrier here for me personally is that I don't have TypeScript skills, so I would need to defer back to the Cypress.io team as repo owner or perhaps to a community member to submit a PR. It would probably need not only just a type definition added, but also some related TypeScript tests together with documentation updates.

BTW: I'm not actually the official maintainer of this repo although by now I am the top contributor in terms of commit count. I just have triage privileges granted to me.

[MikeMcC399]

• @mdmower submitted PR feat: add type declaration file #279 to resolve this issue

[MikeMcC399]

@Kapcash

This plugin, when imported from a .ts file, throws types error because it doesn't declare any types.

• Do you have any exact steps to reproduce, or a failing repo that you could share, so that the proposed resolution from PR feat: add type declaration file #279 can be verified?

Where are your errors thrown? VS Code? tsc or somewhere else?

[MikeMcC399]

Reproducible error here:

Using eslint@9.36.0 and eslint-plugin-cypress@5.1.1, released Aug 4, 2025

git clone https://github.com/cypress-io/cypress-realworld-app
cd cypress-realworld-app
npm install yarn@latest -g
yarn upgrade eslint eslint-plugin-cypress --latest
mv eslint.config.mjs eslint.config.ts
code eslint.config.ts

Hover over import pluginCypress from 'eslint-plugin-cypress' and read:

Could not find a declaration file for module 'eslint-plugin-cypress'. '<dir>/cypress-io/cypress-realworld-app/node_modules/eslint-plugin-cypress/lib/flat.js' implicitly has an 'any' type.
  Try `npm i --save-dev @types/eslint-plugin-cypress` if it exists or add a new declaration (.d.ts) file containing `declare module 'eslint-plugin-cypress';`ts(7016)

[jennifer-shehane]

🎉 This issue has been resolved in version 5.2.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[MikeMcC399]

@Kapcash & @nbouvrette

Please check if eslint-plugin-cypress@5.2.0 resolves the issue for you!