Starter ESLint config

.eslintrc.js

const IS_PROD = process.env.NODE_ENV === "production"

/** @type {import("prettier").Options} */
const prettierRc = {
  arrowParens: "always",
  endOfLine: "lf",
  quoteProps: "consistent",
  semi: false,
  trailingComma: "es5",
}

/** @type {import("eslint").Linter.BaseConfig} */
module.exports = {
  root: true,
  env: { node: true },
  extends: ["plugin:vue/recommended", "eslint:recommended", "@vue/prettier"],
  parserOptions: {
    parser: "babel-eslint",
  },
  rules: {
    "complexity": ["warn", { max: 6 }],
    "max-depth": ["warn", { max: 2 }],
    "max-nested-callbacks": ["warn", { max: 2 }],
    "max-params": ["warn", { max: 3 }],
    "no-console": IS_PROD ? "error" : "off",
    "no-debugger": IS_PROD ? "error" : "off",
    "prettier/prettier": ["error", prettierRc],
    "vue/component-tags-order": "off",
    "vue/valid-v-slot": "off", // See vuejs/eslint-plugin-vue#1229
  },

  overrides: [
    {
      files: [
        "**/__tests__/*.{j,t}s?(x)",
        "tests/unit/setup.js",
        "tests/unit/**/*.spec.{j,t}s?(x)",
      ],
      env: {
        mocha: true,
      },
      rules: {
        "max-nested-callbacks": "off",
        "import/no-extraneous-dependencies": "off",
      },
    },
    {
      files: "src/lang/*.js",
      excludedFiles: "src/lang/index.js",
      rules: {
        "no-irregular-whitespace": "off",
        "prettier/prettier": ["error", { ...prettierRc, printWidth: 999 }],
      },
    },
  ],
}

.vscode_settings.json

{
  "editor.codeActionsOnSave": [
    "source.fixAll.eslint",
  ],
  "editor.insertSpaces": true,
  "editor.renderWhitespace": "boundary",
  "editor.rulers": [80],
  "editor.tabSize": 2,
  "files.eol": "\n",
  "files.insertFinalNewline": true,
  "files.trimTrailingWhitespace": true,
  "javascript.preferences.importModuleSpecifierEnding": "js",
  "search.exclude": {
    ".nyc_output": true,
    "coverage": true,
    "dist": true,
  },
}

package.json

{
  "scripts": {
    "lint": "eslint --fix --ext .js,.vue --ignore-path .gitignore ."
  },
  "devDependencies": {
    "@vue/cli-plugin-eslint": "3.5.1",
    "@vue/eslint-config-prettier": "4.0.1",
    "eslint": "7.20.0",
    "eslint-plugin-prettier": "3.3.1",
    "eslint-plugin-vue": "7.6.0",
    "prettier": "2.2.1",
  }
}