.eslintrc.js

module.exports = {
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: 'module',
  },
  env: {
    browser: true,
    'jest/globals': true
  },
  rules: {
    'array-callback-return': 'error',
    'default-case': 'error',
    'eol-last': 'error',
    'func-call-spacing': ['error', 'never'],
    'init-declarations': ['error', 'always'],
    'max-len': ['error', { 'ignoreComments': true }, { 'code': 120 }],
    'max-lines-per-function': ['error', { 'max': 30 }],
    'max-lines': ['warn', { 'max': 500 }],
    'no-alert': 'error',
    'no-console': 'error',
    'no-empty-function': 'error',
    'no-extra-parens': 'error',
    'no-extra-semi': 'error',
    'no-new': "error",
    'no-new-func': "error",
    'no-trailing-spaces': 'error',
    'no-unused-vars': "error",
    'semi-spacing': 'error',
    complexity: ["error", 6],
    indent: ['error', 2],
    semi: 'error',
  },
  overrides: [
    {
      files: ['*.ts'],
      parser: '@typescript-eslint/parser',
      plugins: [
        '@typescript-eslint',
      ],
      rules: {
        '@typescript-eslint/array-type': 'error',
        '@typescript-eslint/consistent-type-assertions': 'error',
        '@typescript-eslint/explicit-function-return-type': 'error',
        '@typescript-eslint/explicit-module-boundary-types': 'error',
        '@typescript-eslint/member-delimiter-style': 'error',
        '@typescript-eslint/member-ordering': 'error',
        '@typescript-eslint/method-signature-style': 'error',
        '@typescript-eslint/naming-convention': 'error',
        '@typescript-eslint/no-confusing-non-null-assertion': 'error',
        '@typescript-eslint/no-empty-interface': 'error',
        '@typescript-eslint/no-extra-non-null-assertion': 'error',
        '@typescript-eslint/no-misused-new': 'error',
        '@typescript-eslint/no-require-imports': 'error',
        '@typescript-eslint/type-annotation-spacing': 'error',
        '@typescript-eslint/typedef': 'error',
      }
    },
    {
      files: ['*.vue'],
      parser: 'vue-eslint-parser',
      parserOptions: {
        sourceType: 'module',
        ecmaVersion: 2020,
      },
      plugins: [
        'vue',
      ],
      extends: [
        'plugin:vue/recommended',
        'plugin:vue/essential',
      ],
      rules: {
        'vue/html-indent': ['error', 4],
        'vue/multiline-html-element-content-newline': 'error',
        'vue/no-dupe-keys': 'error',
        'vue/no-duplicate-attributes': 'error',
        'vue/no-parsing-error': 'error',
        'vue/no-reserved-keys': 'error',
        'vue/no-spaces-around-equal-signs-in-attribute': 'error',
        'vue/no-unused-components': 'error',
        'vue/no-use-v-if-with-v-for': 'error',
        'vue/require-render-return': 'error',
        'vue/require-v-for-key': 'error',
      }
    },
    {
      files: ['*.spec.js'],
      extends: [
        'plugin:jest/recommended',
      ],
      plugins: [
        'jest',
      ],
      rules: {
        'max-lines': 'off',
        'max-lines-per-function': 'off',
        'jest/consistent-test-it': 'error',
        'jest/expect-expect': 'error',
        'jest/no-commented-out-tests': 'error',
        'jest/no-disabled-tests': 'error',
        'jest/no-export': 'error',
        'jest/no-focused-tests': 'error',
        'jest/no-identical-title': 'error',
        'jest/no-mocks-import': 'error',
        'jest/prefer-strict-equal': 'error',
        'jest/prefer-to-be-null': 'error',
        'jest/prefer-to-be-undefined': 'error',
        'jest/prefer-to-contain': 'error',
        'jest/prefer-to-have-length': 'error',
        'jest/valid-expect': 'error',
      }
    }
  ]
};