.eslintrc.yml

---
root: true
# extends:
#   - prettier
env:
  es6: true
  browser: true
  node: true
  jest: true
parser: babel-eslint
parserOptions:
  sourceType: module
  ecmaVersion: 8
  ecmaFeatures:
    impliedStrict: true
    experimentalObjectRestSpread: true
globals:
  PACKAGE: readonly
  VERSION: readonly
plugins:
  - better
  - filenames
  - require-in-package
  - prettier
rules:
  prettier/prettier:
    - 2
    - singleQuote: true
      trailingComma: es5
      semi: false

  # keep filenames consistent
  filenames/match-regex:
    - 2
    - ^([a-zA-Z][a-zA-Z0-9._-]+)$

  # disallow debugging in production code
  no-alert: 2
  no-assert: 0
  no-console: 2
  no-debugger: 1

  # check for missing dependencies
  require-in-package/require-in-package: 2

  # follow (some of) the teachings of Douglas Crockford
  better/no-fors: 2
  better/no-whiles: 2
  better/no-switches: 2
  better/no-typeofs: 2
  better/no-instanceofs: 2
  better/no-nulls: 2
  better/no-deletes: 1
  better/no-exceptions: 0

  # use ES6 features when they're better than the old alternative
  prefer-template: 2
  no-var: 2
  prefer-const:
    - 2
    - destructuring: any
      ignoreReadBeforeAssign: false
  arrow-body-style:
    - 2
    - as-needed
  arrow-parens:
    - 2
    - always
  prefer-destructuring: 2
  prefer-rest-params: 2
  prefer-spread: 2
  prefer-arrow-callback:
    - 2
    - allowNamedFunctions: true

  # disallow constructs that are almost always an error
  no-cond-assign: 2
  no-constant-condition: 2
  no-dupe-args: 2
  no-dupe-keys: 2
  no-duplicate-case: 2
  no-dupe-class-members: 2
  no-empty: 2
  no-empty-pattern: 2
  no-inner-declarations: 2
  no-irregular-whitespace: 2
  no-obj-calls: 2
  no-return-assign: 2
  no-return-await: 2
  no-sparse-arrays: 2
  no-unreachable: 2
  no-unsafe-finally: 2
  no-unsafe-negation: 2
  use-isnan: 2
  valid-typeof: 2
  array-callback-return: 2
  no-global-assign: 2
  no-octal: 2
  no-octal-escape: 2
  no-self-assign: 2
  no-self-compare: 2
  no-unmodified-loop-condition: 2
  no-unused-expressions: 2
  wrap-iife:
    - 2
    - inside
  no-bitwise: 1
  constructor-super: 2
  no-this-before-super: 2
  no-class-assign: 2
  require-yield: 2

  # don't reassign stuff (it confuses things down the line)
  no-ex-assign: 2
  no-func-assign: 2
  no-param-reassign: 2

  # don't do unnecessary things
  no-extra-boolean-cast: 2
  no-extra-semi: 2
  no-undef-init: 2
  no-else-return: 2
  no-extra-bind: 2
  no-useless-call: 2
  no-useless-concat: 2
  no-useless-escape: 2
  no-useless-return: 2
  no-useless-rename: 2
  no-useless-computed-key: 2
  no-useless-constructor: 2

  # help with regexes
  no-control-regex: 2
  no-invalid-regexp: 2
  no-empty-character-class: 2
  no-regex-spaces: 2
  no-div-regex: 2

  # guard a developer from making mistakes
  no-use-before-define: 1
  no-template-curly-in-string: 1
  no-undef: 2
  no-shadow: 2
  no-shadow-restricted-names: 2
  no-unused-vars:
    - 2
    - vars: local
      args: after-used
      argsIgnorePattern: ^_
      varsIgnorePattern: ^_
  no-loop-func: 2
  no-redeclare: 2
  no-catch-shadow: 2
  radix: 2 # by default parseInt will auto-detect the radix, which sometimes causes weird quirks
  require-await: 2
  no-const-assign: 2

  # apply some best practices
  consistent-return: 2 # either do or don't return, make it explicit
  no-empty-function: 2 # if you want a function that doesn't do anything, make it explicit
  no-implicit-coercion: 2 # don't use (less-readable) tricks to do type conversion, make it explicit
  no-caller: 2 # caller is deprecated and inhibits performance, don't use it
  no-eval: 2
  no-implied-eval: 2
  no-new-func: 2 # another type of eval-ing
  no-script-url: 2 # another type of eval-ing
  no-extend-native: 2 # don't modify global objects
  no-labels: 2 # labels quickly lead to GOTO-style coding, avoid at all costs
  no-new: 2 # only instantiate classes when you're planning on reusing them
  no-proto: 2 # __proto__ is deprecated
  no-sequences: 2 # unreadable, prone to cause confusion and/or errors
  no-throw-literal: 2 # when you really have to throw, at least use it right
  no-void: 2 # there's really no reason why you'd need to use void
  no-with: 2 # there's really no reason why you'd need to use with
  prefer-promise-reject-errors: 2 # Errors make promise rejection reasons easier to pinpoint
  no-floating-decimal: 2 # format floating point numbers nicely
  no-lone-blocks: 2 # don't make blocks that have no syntactic meaning
  yoda:
    - 2
    - never
    - exceptRange: true
  strict: 2 # don't be redundant, es6 is strict by default
  no-array-constructor: 2 # avoid some common pitfalls with new Array

  # some OO-specific hints (avoid using this unless really needed)
  class-methods-use-this: 2 #don't make a class method if you're not gonna use this
  no-invalid-this: 1

  # give advice
  complexity: 1
  max-depth: 2
  max-nested-callbacks:
    - 2
    - max: 3
  max-params:
    - 1
    - max: 5
  max-statements:
    - 1
    - max: 30

  # encourage use of newer JS
  no-restricted-properties:
    - 1
    - object: _
      property: extend
      message: use Object.assign instead of _.extend
  no-restricted-globals:
    - 1
    - event
    - length
    - name
    - open

  # some node/commonjs-specific things
  global-require: 2
  no-mixed-requires: 2
  no-new-require: 2
  handle-callback-err: 2
  no-path-concat: 2
  no-process-env: 1
  no-process-exit: 1

  ## naming and properties
  no-underscore-dangle: 0
  func-name-matching: 2
  func-names:
    - 2
    - as-needed
  new-cap: 2
  new-parens: 2

  ## other conventions
  consistent-this:
    - 2
    - self
  func-style:
    - 2
    - declaration
    - allowArrowFunctions: true
  no-continue: 2
  no-lonely-if: 2
  no-multi-assign: 2
  no-new-object: 2
  no-new-symbol: 2
  no-duplicate-imports: 2
  symbol-description: 2