.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";

const xpcshellTestConfig = require("eslint-plugin-mozilla/lib/configs/xpcshell-test.js");
const browserTestConfig = require("eslint-plugin-mozilla/lib/configs/browser-test.js");

module.exports = {
  "root": true,
  "env": {
    "es6": true,
    "webextensions": true,
  },
  "parser": "babel-eslint",

  "parserOptions": {
    "ecmaVersion": 11
  },

  "globals": {
    "messenger": true
  },

  "extends": [
    "plugin:mozilla/recommended",
  ],
  "plugins": [
    "mozilla",
  ],

  "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,
    "mozilla/var-only-at-top-level": 1,

    // 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,

    "mozilla/mark-test-function-used": 1,

    // 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": 2,

    // 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,
  },
  overrides: [{
    globals: xpcshellTestConfig.globals,
    files: ["test/xpcshell/**"],
    rules: {
      ...xpcshellTestConfig.rules,
      "func-names": "off",
      "mozilla/import-headjs-globals": "error",
    },
  }]
};