Migrating from TSLint to ESLint in a TypeScript project

Showcase the steps and code modifications needed to migrate a TypeScript project from using TSLint to using ESLint.

npm uninstall tslint typescript-tslint-plugin
npm install --save-dev eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin

Uninstall TSLint and TSLint TypeScript plugin, then install ESLint with its TypeScript parser and plugin.

npm install --save-dev eslint-config-prettier eslint-plugin-prettier

Optional: Install ESLint integrations for Prettier if prettier formatting is used.

{
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/eslint-recommended",
    "plugin:@typescript-eslint/recommended"
  ],
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaVersion": 2020,
    "sourceType": "module"
  },
  "plugins": [
    "@typescript-eslint"
  ],
  "rules": {
    // Specify ESLint rules here
  }
}

Create a new `.eslintrc.json` configuration file for ESLint with recommended settings for TypeScript.

npx tslint-to-eslint-config

Optional: Run the tslint-to-eslint-config utility to help migrate TSLint rules to ESLint.

// package.json
{
  "scripts": {
    // Update linting script to use eslint instead of tslint
    "lint": "eslint . --ext .ts,.tsx"
  }
}

Update the `lint` script in `package.json` to use ESLint instead of TSLint.

// Before: Using TSLint
/* tslint:disable */
// Your TypeScript code here
/* tslint:enable */

// After: Migrated to ESLint
/* eslint-disable */
// Your TypeScript code here
/* eslint-enable */

If you have any code-level TSLint disable/enable comments, replace them with ESLint equivalents.