.eslintrc.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 * Portions Copyright (C) Philipp Kewisch, 2019 */
 "use strict";

 module.exports = {
   "root": true,
   "env": {
     "es6": true,
   },
   "parser": "babel-eslint",
 
   "parserOptions": {
     "ecmaVersion": 11
   },
 
   "globals": {
     "messenger": true
   },
  
   "rules": {
     // Enforce one true brace style (opening brace on the same line)
     // Allow single line (for now) because of the vast number of changes needed
     "brace-style": [2, "1tbs", { allowSingleLine: true }],
 
     // Enforce newline at the end of file, with no multiple empty lines.
     "eol-last": 2,
 
     // Disallow using variables outside the blocks they are defined
     "block-scoped-var": 2,
 
     // Allow trailing commas for easy list extension.  Having them does not
     // impair readability, but also not required either.
     "comma-dangle": 0,
 
     // Enforce spacing before and after comma
     "comma-spacing": [2, { before: false, after: true }],
 
     // Enforce one true comma style.
     "comma-style": [2, "last"],
 
     // We should get better at complexity, but at the moment it is what it is
     complexity: [2, 90],
 
     // Enforce curly brace conventions for all control statements.
     curly: 2,
 
     // Require space before/after arrow function's arrow
     "arrow-spacing": [2, { before: true, after: true }],
 
     // Enforces spacing between keys and values in object literal properties.
     "key-spacing": [2, { beforeColon: false, afterColon: true, mode: "minimum" }],
 
     // Disallow the omission of parentheses when invoking a constructor with no
     // arguments.
     "new-parens": 2,
 
     // Disallow use of the Array constructor.
     "no-array-constructor": 2,
 
     // disallow use of the Object constructor
     "no-new-object": 2,
 
     // Disallow Primitive Wrapper Instances
     "no-new-wrappers": 2,
 
     // Disallow the catch clause parameter name being the same as a variable in
     // the outer scope, to avoid confusion.
     "no-catch-shadow": 2,
 
     // Disallow assignment in conditional expressions.
     "no-cond-assign": 2,
 
     // Disallow use of debugger.
     "no-debugger": 2,
 
     // Disallow deletion of variables (deleting properties is fine).
     "no-delete-var": 2,
 
     // Disallow duplicate arguments in functions.
     "no-dupe-args": 2,
 
     // Disallow duplicate keys when creating object literals.
     "no-dupe-keys": 2,
 
     // Disallow a duplicate case label.
     "no-duplicate-case": 2,
 
     // Disallow the use of empty character classes in regular expressions.
     "no-empty-character-class": 2,
 
     // Disallow assigning to the exception in a catch block.
     "no-ex-assign": 2,
 
     // Disallow adding to native types
     "no-extend-native": 2,
 
     // Disallow double-negation boolean casts in a boolean context.
     "no-extra-boolean-cast": 2,
 
     // Disallow unnecessary semicolons.
     "no-extra-semi": 2,
 
     // Disallow mixed spaces and tabs for indentation.
     "no-mixed-spaces-and-tabs": 2,
 
     // Disallow reassignments of native objects.
     "no-native-reassign": 2,
 
     // Disallow nested ternary expressions, they make the code hard to read.
     "no-nested-ternary": 2,
 
     // Disallow use of octal literals.
     "no-octal": 2,
 
     // Disallow comparisons where both sides are exactly the same.
     "no-self-compare": 2,
 
     // Disallow sparse arrays, eg. let arr = [,,2].
     // Array destructuring is fine though:
     // for (let [, breakpointPromise] of aPromises)
     "no-sparse-arrays": 2,
 
     // Disallow trailing whitespace at the end of lines.
     "no-trailing-spaces": 2,
 
     // Disallow use of the with statement.
     "no-with": 2,
 
     // Disallow comparisons with the value NaN.
     "use-isnan": 2,
 
     // Ensure that the results of typeof are compared against a valid string.
     "valid-typeof": 2,
 
     // disallow the use of object properties of the global object (Math and
     // JSON) as functions
     "no-obj-calls": 2,
 
     // disallow use of octal escape sequences in string literals, such as
     // var foo = "Copyright \251";
     "no-octal-escape": 2,
 
     // disallow use of void operator
     "no-void": 2,
 
     // Disallow Yoda conditions (where literal value comes first).
     yoda: 2,
 
     // Require a space immediately following the // in a line comment.
     "spaced-comment": [2, "always"],
 
     // Require use of the second argument for parseInt().
     radix: 2,
 
     // Require spaces before/after unary operators (words on by default,
     // nonwords off by default).
     "space-unary-ops": [2, { words: true, nonwords: false }],
 
     // Enforce spacing after semicolons.
     "semi-spacing": [2, { before: false, after: true }],
 
     // Disallow the use of Boolean literals in conditional expressions.
     "no-unneeded-ternary": 2,
 
     // Disallow use of multiple spaces (sometimes used to align const values,
     // array or object items, etc.). It's hard to maintain and doesn't add that
     // much benefit.
     "no-multi-spaces": [2, { ignoreEOLComments: true }],
 
     // Require spaces around operators, except for a|0.
     // Disabled for now given eslint doesn't support default args yet
     // "space-infix-ops": [2, { "int32Hint": true }],
     "space-infix-ops": 0,
 
     // Require a space around all keywords.
     "keyword-spacing": 2,
 
     // Disallow space between function identifier and application.
     "no-spaced-func": 2,
 
     // Disallow shadowing of names such as arguments.
     "no-shadow-restricted-names": 2,
 
     // Disallow use of comma operator.
     "no-sequences": 2,
 
     // Disallow use of assignment in return statement. It is preferable for a
     // single line of code to have only one easily predictable effect.
     "no-return-assign": 2,
 
     // Require return statements to either always or never specify values
     "consistent-return": 2,
 
     // Disallow padding within blocks.
     "padded-blocks": [2, "never"],
 
     // Disallow spaces inside parentheses.
     "space-in-parens": [2, "never"],
 
     // Require space after keyword for anonymous functions, but disallow space
     // after name of named functions.
     "space-before-function-paren": [2, { anonymous: "never", named: "never" }],
 
     // Disallow unreachable statements after a return, throw, continue, or break
     // statement.
     "no-unreachable": 2,
 
     // Always require use of semicolons wherever they are valid.
     semi: [2, "always"],
 
     // Disallow empty statements. This will report an error for:
     // try { something(); } catch (e) {}
     // but will not report it for:
     // try { something(); } catch (e) { /* Silencing the error because ...*/ }
     // which is a valid use case.
     "no-empty": 2,
 
     // Disallow declaring the same variable more than once (we use let anyway).
     "no-redeclare": 2,
 
     // Warn about declaration of variables already declared in the outer scope.
     // This isn't an error because it sometimes is useful to use the same name
     // in a small helper function rather than having to come up with another
     // random name.  Still, making this a warning can help people avoid being
     // confused.
     "no-shadow": 2,
 
     // We use var-only-at-top-level instead of no-var as we allow top level
     // vars.
     "no-var": 0,
 
     // Disallow global and local variables that aren't used, but allow unused function arguments.
     //"no-unused-vars": [2, { vars: "all", args: "none", varsIgnorePattern: "EXPORTED_SYMBOLS" }],
     "no-unused-vars": 0,
  
     // Require padding inside curly braces
     "object-curly-spacing": [2, "always"],
 
     // Disallow spaces inside of brackets
     "array-bracket-spacing": [2, "never"],
 
     // Disallow control characters in regular expressions
     "no-control-regex": 2,
 
     // Disallow invalid regular expression strings in RegExp constructors
     "no-invalid-regexp": 2,
 
     // Disallow multiple spaces in regular expression literals
     "no-regex-spaces": 2,
 
     // Disallow irregular whitespace
     "no-irregular-whitespace": 2,
 
     // Disallow negating the left operand in `in` expressions
     "no-negated-in-lhs": 2,
 
     // Allow constant expressions in conditions
     // With 2.11.0 we can enable this with checkLoops: false
     "no-constant-condition": [2, { checkLoops: false }],
 
     // Disallow Regexs That Look Like Division
     "no-div-regex": 2,
 
     // Disallow Iterator (using __iterator__)
     "no-iterator": 2,
 
     // Enforce consistent linebreak style
     "linebreak-style": [2, "unix"],
 
     // Enforces return statements in callbacks of array's methods
     "array-callback-return": 2,
 
     // Verify super() calls in constructors
     "constructor-super": 2,
 
     // Disallow modifying variables of class declarations
     "no-class-assign": 2,
 
     // Disallow modifying variables that are declared using const
     "no-const-assign": 2,
 
     // Disallow duplicate name in class members
     "no-dupe-class-members": 2,
 
     // Disallow use of this/super before calling super() in constructors
     "no-this-before-super": 2,
 
     // Disallow duplicate imports
     "no-duplicate-imports": 2,
 
     // Disallow empty destructuring patterns
     "no-empty-pattern": 2,
 
     // Disallow Labeled Statements
     "no-labels": 2,
 
     // Disallow Multiline Strings
     "no-multi-str": 2,
 
     // Disallow Symbol Constructor
     "no-new-symbol": 2,
 
     // Disallow Initializing to undefined
     "no-undef-init": 2,
 
     // Disallow control flow statements in finally blocks
     "no-unsafe-finally": 2,
 
     // Disallow Unused Labels
     "no-unused-labels": 2,
 
     // Disallow unnecessary computed property keys on objects
     "no-useless-computed-key": 2,
 
     // Disallow unnecessary constructor
     "no-useless-constructor": 2,
 
     // Disallow renaming import, export, and destructured assignments to the
     // same name
     "no-useless-rename": 2,
 
     // Enforce spacing between rest and spread operators and their expressions
     "rest-spread-spacing": [2, "never"],
 
     // Disallow usage of spacing in template string expressions
     "template-curly-spacing": [2, "never"],
 
     // Disallow the Unicode Byte Order Mark
     "unicode-bom": [2, "never"],
 
     // Enforce spacing around the * in yield* expressions
     "yield-star-spacing": [2, "after"],
 
     // Disallow Implied eval
     "no-implied-eval": 2,
 
     // Disallow unnecessary function binding
     "no-extra-bind": 2,
 
     // Disallow new For Side Effects
     "no-new": 2,
 
     // Disallow Self Assignment
     "no-self-assign": 2,
 
     // Disallow confusing multiline expressions
     "no-unexpected-multiline": 2,
 
     // Require IIFEs to be Wrapped
     "wrap-iife": [2, "inside"],
 
     // Disallow Unused Expressions
     "no-unused-expressions": 2,
 
     // Disallow function or var declarations in nested blocks
     "no-inner-declarations": 2,
 
     // Enforce newline before and after dot
     "dot-location": [2, "property"],
 
     // Disallow Use of caller/callee
     "no-caller": 2,
 
     // Disallow Case Statement Fallthrough
     "no-fallthrough": 2,
 
     // Disallow Floating Decimals
     "no-floating-decimal": 2,
 
     // Require Space Before Blocks
     "space-before-blocks": 2,
 
     // Operators always before the line break
     "operator-linebreak": [2, "after", { overrides: { ":": "before", "?": "ignore" } }],
 
     // Restricts the use of parentheses to only where they are necessary
     // Disabled for now since this also removes parens around assignments, e.g. let foo = bar == baz
     // "no-extra-parens": [2, "all", { "conditionalAssign": false, "returnAssign": false, "nestedBinaryExpressions": false }],
 
     // Double quotes should be used.
     quotes: [2, "double", { avoidEscape: true }],
 
     // Disallow if as the only statement in an else block.
     "no-lonely-if": 2,
 
     // Not more than two empty lines with in the file, and no extra lines at
     // beginning or end of file.
     "no-multiple-empty-lines": [2, { max: 2, maxEOF: 0, maxBOF: 0 }],
 
     // Make sure all setters have a corresponding getter
     "accessor-pairs": 2,
 
     // Enforce spaces inside of single line blocks
     "block-spacing": [2, "always"],
 
     // Disallow spaces inside of computed properties
     "computed-property-spacing": [2, "never"],
 
     // Require consistent this (using |self|)
     "consistent-this": [2, "self"],
 
     // Disallow unnecessary .call() and .apply()
     "no-useless-call": 2,
 
     // Require dot notation when accessing properties
     "dot-notation": 2,
 
     // Disallow named function expressions
     "func-names": [2, "never"],
 
     // Enforce placing object properties on separate lines
     "object-property-newline": [2, { allowMultiplePropertiesPerLine: true }],
 
     // Do Not Require Object Literal Shorthand Syntax
     // (Override the parent eslintrc setting for this.)
     "object-shorthand": "off",
 
     // Disallow whitespace before properties
     "no-whitespace-before-property": 2,
 
     // Disallow unnecessary escape usage
     "no-useless-escape": 2,
 
     // Disallow mixes of different operators, but allow simple math operations.
     "no-mixed-operators": [
       2,
       {
         groups: [
           /* ["+", "-", "*", "/", "%", "**"], */
           ["&", "|", "^", "~", "<<", ">>", ">>>"],
           ["==", "!=", "===", "!==", ">", ">=", "<", "<="],
           ["&&", "||"],
           ["in", "instanceof"],
         ],
       },
     ],
 
     // Disallow unnecessary concatenation of strings
     "no-useless-concat": 2,
 
     // Disallow unmodified conditions of loops
     "no-unmodified-loop-condition": 2,
 
     // Suggest using arrow functions as callbacks
     "prefer-arrow-callback": [2, { allowNamedFunctions: true }],
 
     // Suggest using the spread operator instead of .apply()
     "prefer-spread": 2,
 
     // Disallow negated conditions
     "no-negated-condition": 0,
 
     // Enforce a maximum number of statements allowed per line
     "max-statements-per-line": [2, { max: 2 }],
 
     // Disallow arrow functions where they could be confused with comparisons
     "no-confusing-arrow": 2,
 
     // Disallow Unnecessary Nested Blocks
     "no-lone-blocks": 2,
 
     // Enforce minimum identifier length
     "id-length": [
       2,
       {
         min: 3,
         exceptions: [
           /* sorting */
           "a",
           "b",
           /* exceptions */
           "e",
           "ex",
           /* loop indices */
           "i",
           "j",
           "k",
           "n",
           /* coordinates */
           "x",
           "y",
           /* regexes */
           "re",
           /* known words */
           "rc",
           "rv",
           "id",
           "OS",
           "os",
           "db",
           "is",
           /* mail/calendar words */
           "to",
           "cc",
           /* Components */
           "Ci",
           "Cc",
           "Cu",
           "Cr",
         ],
       },
     ],
 
     // Disallow lexical declarations in case/default clauses
     "no-case-declarations": 2,
 
     // The following rules will not be enabled currently, but are kept here for
     // easier updates in the future.
     "no-else-return": 0,
   },
 };