@wise/eslint-config

A modular ESLint config used at Wise.

Usage

1. Install the package as a dev dependency along with ESLint:

   pnpm add --save-dev @wise/eslint-config

2. Extend your ESLint configuration as follows:

   // .eslint.config.js
   import baseStrict from '@wise/eslint-config/base-strict';
   import react from '@wise/eslint-config/react';
   import next from '@wise/eslint-config/next';
   import jest from '@wise/eslint-config/jest';
   import cypress from '@wise/eslint-config/cypress';
   import storybook from '@wise/eslint-config/storybook';
   import testingLibrary from '@wise/eslint-config/testing-library-react';
   
   export default [
     /* Recommended for all projects, includes TypeScript rules. */
     ...baseStrict, // you can import from '@wise/esltin-config/base' instead
   
     /* Uncomment lines in the order below as you adopt each technology */
     // ...react,
     // ...next,
     // ...jest,
     // ...cypress,
     // ...storybook,
     // ...testingLibrary,
   ];

3. If you’re using a monorepo with TypeScript, please set parserOptions.projectService = true as per the docs of typescript-eslint.

Script setup

Set up your package.json scripts to run the linting on the CLI. We recommend adhering to ESLint’s package.json conventions for naming scripts.

// package.json
{
  "scripts": {
    /* TypeScript-specific logic may be enabled as hinted by comments below */
    "lint": "pnpm run lint:js+ts && pnpm run lint:format", // && pnpm run lint:types
    "lint:js+ts": "eslint '**/*.{js,jsx,mjs,cjs,ts,tsx,mts,cts}'",
    "lint:format": "prettier \"**/*\" --check --ignore-unknown",
    // "lint:types": "tsc --noEmit",
    "lint:fix": "pnpm run lint:fix:js+ts && pnpm run lint:fix:format",
    "lint:fix:js+ts": "pnpm run lint:js+ts --fix",
    "lint:fix:format": "prettier \"**/*\" --write --ignore-unknown",
  },
}

Compatibility with Prettier

Stylistic linting rules which may conflict with Prettier are turned off.

We encourage developers to use Prettier’s opinionated defaults with no additional configuration.

Lint and format on commit

1. Install packages as follows:

   pnpm add --save-dev husky nano-staged

2. Configure scripts to be run on staged files:

   // package.json
   "nano-staged": {
     "*": "prettier --write --ignore-unknown",
     "*.{js,jsx,mjs,cjs,ts,tsx,mts,cts}": "eslint --fix",
   }

3. Configure git hooks via Husky:

   pnpm exec husky
   echo "pnpm exec nano-staged" > .husky/pre-commit
   npm pkg set scripts.prepare="husky || cd ."

   The || cd . part sets the exit code to zero in a cross-platform manner when husky isn’t found, e.g. when devDependencies aren’t installed.

Auto-fix on save in your IDE

VS Code

Extend your editor configuration as follows:

// .vscode/settings.json
{
  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit",
  },
}

Contributing

If you think a rule should be added or changed, please create a pull request. Releases are managed via Changesets and follow Semantic Versioning conventions.

Troubleshooting

Rules of our configs shouldn’t be turned off or overridden in general. When encountering a false-positive, please disable it via eslint-disable-next-line or eslint-disable and consider filing an issue to the Web Guild.

Import issues

The first time you integrate with the config, you might get a lot of import issues.

  1:1  warning  Run autofix to sort these imports!  simple-import-sort/imports

This error is auto-fixable using the --fix option.

Unable to resolve path to module (import/no-unresolved)

When trying to import from a .d.ts file, import type should be used over import, e.g.:

- import { AlertType } from "@transferwise/components/build/types/alert/Alert";
+ import type { AlertType } from "@transferwise/components/build/types/alert/Alert";

Furthermore, setting verbatimModuleSyntax in TSConfig is recommended to avoid these issues and deal with side-effects explicitly.

Using TypeScript

When using multiple configuration files in tsconfig.json, e.g. extends: ["array", "of", "tsconfigs"], the following error may occur:

TypeError: The "path" argument must be of type string. Received an instance of Array

This happens because eslint-import-resolver-typescript doesn’t support the array extends syntax introduced by TypeScript 5.

Please don’t extend from multiple TSConfigs at this time.

Parsing error

When linting JavaScript without types, the following error may occur:

You appear to be using a native ECMAScript module configuration file, which is only supported when running Babel asynchronously

This happens if your Babel configuration uses ECMAScript module syntax. By migrating to JSON or using CommonJS, the issue can be mitigated, e.g.:

  // babel.config.js
- export default { /* … */ };
+ module.exports = { /* … */ };

ESLint couldn't determine the plugin uniquely

Sometimes, if you integrate, you might see an error similar to this

Oops! Something went wrong! :(

ESLint: 9.13.0

ConfigError: Config (unnamed): Key "plugins": Cannot redefine plugin "import".
...

Most of the time, removing the offending plugin (in this case, import) in your config file should solve the issue.

What this means is that the said plugin is already imported by a previous config. Importing them again will cause the issue.