.eslintrc.js

module.exports = {
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: "module",
  },
  env: {
    es6: true,
    node: true, // for config files
  },
  extends: ["eslint:recommended", "prettier"],
  overrides: [
    {
      files: ["**/*.svelte"],
      plugins: ["svelte3"], // no plugin:prettier/recommended, it enables eslint-plugin-prettier
      processor: "svelte3/svelte3",
      env: { browser: true, node: false },
      settings: {
        "svelte3/ignore-styles": () => true,
      },
      // no prettier/prettier rule, it makes eslint run prettier
    },
    {
      files: ["*.js", "*.spec.js"],
      extends: ["plugin:prettier/recommended"],
      env: { browser: true, node: false },
      rules: {
        "prettier/prettier": "error",
      },
    },
    {
      files: ["*.spec.js"],
      env: {
        browser: false,
        jest: true,
      },
    },
  ],
};