.eslintrc.js

const readonly = 'readonly';
const error = 'error';
const warn = 'warn';
const off = 'off';

module.exports = {
  extends: [
    'airbnb-base',
  ],
  env: {
    es6: true,
    browser: true,
    jquery: true,
    greasemonkey: true,
    node: false,
  },
  globals: {
    BootstrapDialog: readonly,
    SimpleToast: readonly,
  },
  parserOptions: {
    sourceType: 'module',
  },
  rules: {
    // Warn, we allow this behavior, but want to be aware of any possible issues
    'consistent-return': warn,
    // We allow modification of properties
    'no-param-reassign': [warn, { props: false }],
    // Allow short circuits: test && action
    'no-unused-expressions': [error, { allowShortCircuit: true }],
    // Allow function arguments to be unused
    'no-unused-vars': [error, { args: 'none' }],
    // Allow functions to be defined after references (functions are top-level)
    'no-use-before-define': [error, 'nofunc'],
    // Deconstruction not required when assigning to object properties (declared_var = object.key)
    'prefer-destructuring': [error, {
      AssignmentExpression: { array: true, object: false },
    }],
    // Allow for loops to use unary (++/--)
    'no-plusplus': [error, { allowForLoopAfterthoughts: true }],
    'prefer-arrow-callback': [error, { allowNamedFunctions: true } ],
    'no-useless-return': warn,
    'class-methods-use-this': off,
    'no-restricted-globals': [error, ''],
    'no-bitwise': off,
    'no-mixed-operators': off,
    'no-continue': off,
    'object-curly-newline': [error, { multiline: true, consistent: true }],
    'operator-linebreak': [error, 'after'],
    'quotes': [error, 'single', { allowTemplateLiterals: true, }],
    'max-len': [error, { 
      code: 120,
      ignoreComments: true,
      ignoreRegExpLiterals: true,
      ignoreStrings: true,
      tabWidth: 2,
    }],
    'no-extra-boolean-cast': warn,
    'no-underscore-dangle': warn,
    'import/no-mutable-exports': warn,
  },
};