.eslintrc.js

/* eslint-env node */
module.exports = {
  plugins: ['@typescript-eslint', 'svelte'],
  extends: [
    'eslint:recommended',
    'plugin:svelte/recommended',
    // 'plugin:@typescript-eslint/recommended',
    // 'plugin:@typescript-eslint/recommended-requiring-type-checking',
  ],
  parser: '@typescript-eslint/parser', // add the TypeScript parser
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: 'module',
    tsconfigRootDir: __dirname,
    project: ['./tsconfig.eslint.json'],
    extraFileExtensions: ['.svelte'],
  },
  env: {
    node: true,
    es6: true,
    browser: true,
    jest: true,
  },
  overrides: [
    {
      files: ['*.svelte'],
      parser: 'svelte-eslint-parser',
      // Parse the `<script>` in `.svelte` as TypeScript by adding the following configuration.
      parserOptions: {
        parser: '@typescript-eslint/parser',
      },
    },
    {
      files: ['*.ts'],
      extends: [
        'eslint:recommended',
        'plugin:@typescript-eslint/recommended',
        'plugin:@typescript-eslint/recommended-requiring-type-checking',
      ],
      rules: {
        '@typescript-eslint/no-non-null-assertion': 'off',
        '@typescript-eslint/no-unnecessary-type-assertion': 'off', // generate as a bunch of false positives
        '@typescript-eslint/no-base-to-string': 'off', // false positives in deriveLinkDefaults
      },
    },
  ],
};