.eslintrc.js

//https://eslint.org/docs/user-guide/configuring

module.exports = {
  root: true,
  parserOptions: {
    parser: 'babel-eslint',
    ecmaVersion: 8,
  },
  env: {
    browser: true,
    mocha: true,
    jasmine: true,
    es6: true,
  },
  //https://github.com/vuejs/eslint-plugin-vue#priority-a-essential-error-prevention
  //consider switching to `plugin:vue/strongly-recommended` or `plugin:vue/recommended` for stricter rules.
  extends: ['plugin:vue/recommended', 'airbnb-base'],
  //required to lint *.vue files
  plugins: [
    'vue',
    'html',
  ],
  //check if imports actually resolve
  settings: {
    'import/resolver': {
      webpack: {
        config: './.webpack.config.js',
      },
    },
  },
  //add your custom rules here
  rules: {

    /**
    * Allowances
    */

    'vue/max-attributes-per-line': 'off',
    'no-plusplus': 0,
    'no-inner-declarations': 0,
    'class-methods-use-this': [0, { exceptMethods: ['data', 'computed'] }],
    'no-underscore-dangle': [2, { allowAfterThis: true }],
    'no-continue': 0,
    /**
    * General
    */

    //This will throw warnings anywhere 'use strict' occurs, which is good.
    strict: [2, 'never'],

    /**
    * Errors
    */

    curly: [2, 'multi-line'],
    'no-cond-assign': [2, 'always'], //This is why you should yoda :p
    'no-constant-condition': 2,
    'no-dupe-keys': 2,
    'no-duplicate-case': 2,
    'no-else-return': 2,
    'no-eq-null': 2,
    'no-eval': 2,
    'no-ex-assign': 2,
    'no-extend-native': 2,
    'no-extra-bind': 2,
    'no-extra-semi': 2,
    'no-func-assign': 2,
    'no-implied-eval': 2,
    'no-invalid-regexp': 2,
    'no-irregular-whitespace': 2,
    'no-lone-blocks': 2,
    'no-loop-func': 2,
    'no-native-reassign': 2,
    'no-new': 2,
    'no-new-func': 2,
    'no-new-wrappers': 2,
    'no-obj-calls': 2,
    'no-octal': 2,
    'no-octal-escape': 2,
    'no-proto': 2,
    'no-redeclare': 2,
    'no-return-assign': 2,
    'no-script-url': 2, //No need for these in Meteor!
    'no-self-compare': 2,
    'no-sequences': 2, //I hate that!
    'no-shadow': [1, { hoist: 'functions' }],
    'no-sparse-arrays': 2,
    'no-unreachable': 2,
    'no-with': 2,
    'use-isnan': 2,
    'wrap-iife': [2, 'any'],

    //don't require .vue extension when importing
    'import/extensions': ['error', 'always', {
      js: 'never',
      vue: 'never',
    }],
    //disallow reassignment of function parameters
    //disallow parameter object manipulation except for specific exclusions
    'no-param-reassign': ['error', { props: false }],
    //allow optionalDependencies
    'import/no-extraneous-dependencies': 'error',
    'max-len': 'off',
    eqeqeq: 'warn',
    //allow debugger during development
    'no-debugger': process.env.NODE_ENV === 'production' ? 'error' : 'off',

    /**
    * Warnings
    */

    'comma-dangle': [1, 'always-multiline'],
    'consistent-return': 1,
    'default-case': 1, //*If* you happen to use a switch, maybe you don't want a default
    'guard-for-in': 1,
    'no-alert': 1,
    'no-caller': 1, //Should be 2, but there is some code out there... ;>
    'no-debugger': 1,
    'no-extra-boolean-cast': 1, //I should give it a 2 but being nice!! (Sasha uses them)
    //^punny, eh! :D
    'no-fallthrough': 1, //*If* you happen to.. it shouldn't be often.
    'no-floating-decimal': 1, //Should be 2, but I bet lots of you...
    'no-multi-str': 1, //Should be 2, I'm being nice :>
    'no-shadow-restricted-names': 2,
    'no-unused-vars': [1, {
      vars: 'local',
      args: 'none',
    }],
    'no-use-before-define': 2,

    /**
    * Style
    */
    'brace-style': [2,
      '1tbs', {
        allowSingleLine: true,
      },
    ],
    camelcase: [2, { properties: 'always' }],
    'comma-spacing': [2, {
      before: false,
      after: true,
    }],
    'comma-style': [2, 'last'],
    indent: [2, 2, { SwitchCase: 1 }],
    'key-spacing': [2, {
      afterColon: true,
      beforeColon: false,
    },
    ], //'prop': x, extra spacing allowed if lining up blocks
    'linebreak-style': [
      2,
      'unix',
    ],
    'new-cap': 2,
    'no-multiple-empty-lines': 1,
    'no-new-object': 2, //There are good reasons not to
    'no-array-constructor': 2, //There are good reasons not to
    'no-trailing-spaces': 2,
    'one-var': [2, 'never'],
    quotes: [
      2, 'single', 'avoid-escape',
    ],
    semi: [2, 'always'],
    'semi-spacing': [2, {
      before: false,
      after: true,
    }],
    'keyword-spacing': [2, {
      after: true,
      overrides: {
        if: { after: false },
        for: { after: false },
        while: { after: false },
        switch: { after: false },
      },
    }],
    'space-before-blocks': 2,
    'space-infix-ops': 2,
    'spaced-comment': [2, 'never'],
  },
  overrides: [
    {
      files: ['*.spec.js'],
      globals: {
        assert: true,
      },
      rules: {
        'func-names': 0,
        'no-empty': [2, { allowEmptyCatch: true }],
      },
    },
  ],
};