Monorepo Configuration

If you're using a monorepo, these docs will help you figure out how to setup typed linting. If you don't want to use typed linting, then you can stop here - you don't need to do anything special.

The first question to answer is how are your tsconfig.json setup? You should have one of two setups:

1. One tsconfig.json per package (and an optional one in the root)
2. One root tsconfig.json

One tsconfig.json per package (and an optional one in the root)

Earlier in our docs on typed linting, we showed you how to setup a config for typed linting using the parserOptions.project option. This option accepts an array of relative paths, allowing you to specify each and every tsconfig.json in your monorepo. For those of you with too many packages, you can also supply a glob path.

For example, this is how we specify all of our tsconfig.json within this repo.

.eslintrc.js

 module.exports = {
   root: true,
   parser: '@typescript-eslint/parser',
   parserOptions: {
     tsconfigRootDir: __dirname,
-    project: ['./tsconfig.json'],
+    project: ['./tsconfig.eslint.json', './packages/*/tsconfig.json'],
   },
   plugins: ['@typescript-eslint'],
   extends: [
     'eslint:recommended',
     'plugin:@typescript-eslint/recommended',
     'plugin:@typescript-eslint/recommended-requiring-type-checking',
   ],
 };

If you're looking for an example of what the .eslintrc.js, and referenced tsconfig.json might look like in a real example, look no further than this very repo. We're a multi-package monorepo that uses one tsconfig.json per package, that also uses typed linting.

Important note regarding large (> 10) multi-package monorepos

We've had reports that for sufficiently large and/or interdependent projects, you may run into OOMs using this approach. Our advice is to set it up and test first, as there are very few cases that trigger this OOM. We are in the process of investigating solutions with the help of the TypeScript team.

See #1192 for more information and discussion.

If you do run into an OOM, please comment on the above issue and let us know about your repo - the more information we have, the better. As an interim workaround, consider one of the following:

• Switching to one root tsconfig.eslint.json (see below)
• Using a shell script to only lint one package at a time, using your existing config above.

One root tsconfig.json

If you've only got one, you should inspect the include paths. If it doesn't include all of your files, then we won't be able to lint them. In this instance, you have two options: add them in to the include, or create a new config.

The former doesn't always work for everyone if they've got a complex build, as adding more paths (like test paths) to include could break the build. In those cases we suggest creating a new config called tsconfig.eslint.json, that looks something like this:

tsconfig.eslint.json

{
  // extend your base config to share compilerOptions, etc
  "extends": "./tsconfig.json",
  "compilerOptions": {
    // ensure that nobody can accidentally use this config for a build
    "noEmit": true
  },
  "include": [
    // whatever paths you intend to lint
    "src",
    "test",
    "tools"
  ]
}

Ensure you update your .eslintrc.js to point at this new config file.

Troubleshooting

If you're having problems getting this working, please have a look at our Troubleshooting FAQ.