@pkerschbaum/typescript-eslint-rules-requiring-type-info

Problem

Some typescript-eslint rules require type information. Enabling them provides real benefits, e.g. no-floating-promises catches cases in which one might forgot to await a promise.

However, if at least one rule requiring type information is enabled, the time it takes to lint increases significantly. See this page for more information.
This is usually OK if linting is done via the eslint CLI; however, in an IDE (especially if autofix-on-save is enabled), this can be very annoying.
Depending on the size of the TypeScript codebase, it might even happen that saving a file takes a couple of seconds because of these linting rules.

Solution

Only lint using rules requiring type information when the eslint CLI is used. Disable those rules when using an IDE like VS Code.
This way the IDE stays fast but running eslint from the terminal (or as pre-commit hook, in a CI/CD system, ...) still performs an "exhaustive" lint run.

This package exposes two functions to help accomplish this idea:

• fetchAndStoreRules: fetches the list of rules from typescript-eslint.io/rules and stores all rules requiring type information in a JSON file.
• removeTypeInfoRules: given a ESLint config and the JSON file, removes all rules which require type information from the ESLint config.

Installation (in four steps)

1. Install the package:

   npm i --save-dev @pkerschbaum/typescript-eslint-rules-requiring-type-info

2. Run fetchAndStoreRules on a regular basis. You can run it using node in postinstall script of your package.json:

   {
     "scripts": {
       "postinstall": "node --input-type=module -e 'import { fetchAndStoreRules } from \"@pkerschbaum/typescript-eslint-rules-requiring-type-info\"; void fetchAndStoreRules();'"
     }
   }

3. Configure your .eslintrc.cjs file (picked up by IDEs) such that the rules are excluded, like so:

   const {
     removeTypeInfoRules,
   } = require('@pkerschbaum/typescript-eslint-rules-requiring-type-info');
   
   const applyHeavyRules = process.env.APPLY_HEAVY_RULES === 'true';
   
   /**
    * @type {any}
    */
   const eslintConfig = {
     root: true,
     parser: '@typescript-eslint/parser',
     parserOptions: {
       tsconfigRootDir: __dirname,
       project: './tsconfig.json',
     },
     plugins: ['@typescript-eslint/eslint-plugin'],
     extends: [
       'eslint:recommended',
       'plugin:@typescript-eslint/recommended',
       'plugin:@typescript-eslint/recommended-requiring-type-checking',
     ],
   };
   
   /*
    * only if env variable APPLY_HEAVY_RULES is set, we will include the "heavy" @typescript-eslint rules
    */
   module.exports = applyHeavyRules ? eslintConfig : removeTypeInfoRules(eslintConfig);

4. To run all rules when using the eslint CLI, configure a lint script in your package.json (and use that script from the terminal, in pre-commit hooks, in CI/CD, etc.):

   {
     "scripts": {
       "lint": "cross-env APPLY_HEAVY_RULES=true eslint --max-warnings 0 ."
     }
   }