This post goes over how to migrate a project from TypeScript to ESLint since TSLint is deprecated.

Prerequisites

The project should contain the files:

• package.json
• tsconfig.json
• tslint.json

Uninstall

First, uninstall tslint from package.json:

npm remove tslint

Verify typescript is still present:

npm list typescript

Install

Then install eslint and the TypeScript eslint-plugin and parser:

npm install --save-dev eslint @typescript-eslint/{eslint-plugin,parser}

Config

Initialize .eslintrc:

npx eslint --init

Your base .eslintrc should look something like this:

{
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/eslint-recommended"
  ],
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaVersion": 11,
    "sourceType": "module"
  },
  "plugins": ["@typescript-eslint"]
}

Move your tslint.json rules to .eslintrc.

Add env to your .eslintrc (if applicable):

{
  "env": {
    "browser": true,
    "es6": true,
    "jest": true,
    "node": true
  }
}

Script

Update your lint script in package.json:

 {
   "scripts": {
-    "lint": "tslint -c tslint.json 'src/**/*.ts'"
+    "lint": "eslint --ignore-path .gitignore --ext .js,.ts .",
   }
 }

Test that it still works:

npm run lint

Misc

Migrate any TSLint configs/plugins to ESLint (if applicable).

The following example is for Prettier:

npm rm tslint-config-prettier && npm i -D eslint-plugin-prettier

Don’t forget to update .eslintrc:

{
  // ...
  "plugins": ["@typescript-eslint", "prettier"],
  "rules": {
    "prettier/prettier": "error"
  }
}

Here’s a pull request that I opened for phonetic-alphabet-converter.

Lastly, you can use tslint-to-eslint-config to migrate from TSLint to ESLint:

npx tslint-to-eslint-config