.eslintrc.js

module.exports = {
  root: true,
  parser: '@typescript-eslint/parser',
  parserOptions: {
    ecmaVersion: 2017,
    sourceType: 'module',
  },
  plugins: ['prettier', '@typescript-eslint'],
  extends: ['eslint:recommended', 'prettier', 'prettier/@typescript-eslint'],
  env: {
    browser: false,
    node: true,
    es6: true,
    qunit: true,
  },
  rules: {
    'prettier/prettier': 'error',
    'no-unused-vars': 'off',
    '@typescript-eslint/no-unused-vars': 'error',
  },
  overrides: [
    // node files
    {
      files: [
        '.eslintrc.js',
        '.prettierrc.js',
        '.template-lintrc.js',
        'ember-cli-build.js',
        'index.js',
        'testem.js',
        'blueprints/*/index.js',
        'config/**/*.js',
        'tests/dummy/config/**/*.js',
      ],
      excludedFiles: ['addon/**', 'addon-test-support/**', 'app/**', 'tests/dummy/app/**'],
      parserOptions: {
        sourceType: 'script',
        ecmaVersion: 2015,
      },
      env: {
        browser: false,
        node: true,
        es6: true,
      },
      plugins: ['node'],
      rules: Object.assign({}, require('eslint-plugin-node').configs.recommended.rules, {
        // add your custom rules and overrides for node files here
      }),
    },
    {
      files: ['src/tests/**/*.ts'],
      parserOptions: {
        ecmaVersion: 2017,
        sourceType: 'module',
      },
      env: {
        qunit: true,
        node: true,
      },
    },
  ],
};