ESLint plugin

Table of contents

• Overview
• Installation
• Configs
• Rules
• Synonyms
• Custom checks
• Planned rules

Overview

A collection of ESLint rules for:

• JavaScript / TypeScript files
• Jest test files

Installation

npm install --save-dev eslint-plugin-misc

// .eslintrc.js
module.exports = {
  extends: "plugin:misc/all",
  parser: "@typescript-eslint/parser",
  plugins: ["misc"]
};

Configs

• plugin:misc/all — All rules.
• plugin:misc/core — Core rules.
• plugin:misc/eslintrc — Rules for ESLint configuration files.
• plugin:misc/jest — Rules for Jest test files.
• plugin:misc/typescript — Rules for typescript files.

Rules

• class-match-filename — Requires class name to match filename.
• comment-spacing — Requires consistent empty lines around comments.
• consistent-empty-lines — Requires consistent empty lines.
• consistent-enum-members — Requires consistent key-value pairs inside enums (key should match value).
• consistent-filename — Enforces consistent file name format.
• consistent-import — Requires consistent import.
• consistent-optional-props — Ensures consistent optional property style.
• consistent-source-extension — Requires consistent import/export source extension.
• consistent-symbol-description — Requires consistent symbol description.
• disallow-import — Disallows import given sources.
• export-matching-filename-only — Requires that export matching filename is the only export.
• match-filename — Requires that AST element matches filename.
• max-identifier-blocks — Restricts identifier complexity.
• no-at-sign-import — Disallows "@" import.
• no-at-sign-internal-import — Disallows "@/**" import.
• no-chain-coalescence-mixture — Disallows mixing of chain and coalescence operators.
• no-expression-empty-lines — Disallows empty lines inside expressions.
• no-index-import — Disallows "." import.
• no-internal-modules — Disallows importing of internal modules.
• no-language-mixing — Disallows language mixing.
• no-negated-conditions — Disallows negated conditions.
• no-nodejs-modules — Disallows importing NodeJS modules.
• no-param-reassign — This rule wraps "no-param-reassign" core rule, but allows to edit params at the top of function body.
• no-relative-parent-import — Disallows relative parent import.
• no-restricted-syntax — Disallows AST syntax (an extended version of ESLint core rule).
• no-self-import — Disallows self-import.
• no-shadow — This rule wraps "@typescript-eslint/no-shadow" rule, but skips checking enum.
• no-sibling-import — Restricts importing siblings.
• no-underscore-export — Disallows underscore export.
• no-unnecessary-as-const — Disallows unnecessary "as const".
• no-unnecessary-break — Disallows unnecessary "break".
• no-unnecessary-initialization — Disallows unnecessary initialization.
• no-unnecessary-template-literal — Disallows unnecessary template literals.
• object-format — Requires multiline or single-line object format.
• only-export-name — Requires that only export matches filename.
• prefer-arrow-function-property — Requires use of arrow functions.
• prefer-const-require — Requires "require()" to be assigned to variable.
• prefer-only-export — Requires only export if given AST element is found.
• require-jsdoc — Requires JSDoc documentation.
• require-syntax — Requires AST syntax.
• restrict-identifier-characters — Requires that identifier consists only of english characters and dollar sign.
• sort-array — Sorts arrays.
• sort-call-signature — Requires call signature to be first child.
• sort-class-members — Sorts class members by type and alphabetically inside each type group.
• sort-construct-signature — Requires construct signature to be first child.
• sort-export-specifiers — Sorts export specifiers.
• sort-keys — Sorts object keys.
• sort-statements — Sorts statements.
• sort-top-comments — Sorts top comments.
• switch-case-spacing — Ensures consistent empty lines between switch case statements.
• template-literal-format — Requires consistent padding in template literals.
• wrap — Wraps and modifies third-party rule.
• eslintrc/no-message-dot — Disallows dot at the end of message.
• eslintrc/no-unnecessary-array — Disallows unnecessary single-element arrays in eslint configuration files.
• eslintrc/sort-array — Sorts safely sortable arrays in eslint configuration files.
• eslintrc/sort-suboptions — Sorts safely sortable arrays in eslint configuration files.
• jest/no-toThrow-literal — Disallows string argument in "toThrow" matcher.
• jest/prefer-toBe — Requires "toBe" matcher instead of "toStrictEqual" for primitive argument types.
• jest/prefer-toStrictEqual — Requires "toStrictEqual" matcher instead of "toBe" for non-primitive argument types.
• typescript/array-callback-return-type — Requires boolean return type in array callbacks.
• typescript/class-methods-use-this — This rule wraps "class-methods-use-this" core rule, but skips methods with "this: void" argument.
• typescript/consistent-array-type-name — Requires consistent array type name.
• typescript/define-function-in-one-statement — Requires that function is defined in one statement.
• typescript/exhaustive-switch — Checks exhaustiveness of switch statement.
• typescript/no-boolean-literal-type — Disallows boolean literal type.
• typescript/no-complex-declarator-type — Disallow complex declarator types.
• typescript/no-complex-return-type — Disallow complex function return types.
• typescript/no-empty-interfaces — Disallow empty interfaces.
• typescript/no-inferrable-types — Reports inferrable types.
• typescript/no-multi-type-tuples — Disallows multi-type tuples.
• typescript/no-never — Disallow "never" type.
• typescript/no-restricted-syntax — Disallows AST syntax with additional type check.
• typescript/no-unsafe-object-assign — Disallows unsafe "Object.assign".
• typescript/no-unsafe-object-assignment — Reports unsafe object assignments.
• typescript/prefer-array-type-alias — Prefer alias for array type.
• typescript/prefer-class-method — Requires use of class methods instead of function properties.
• typescript/prefer-enum — Requires using enums instead of string literals.
• typescript/prefer-readonly-array — Disallows writable arrays.
• typescript/prefer-readonly-map — Disallows writable maps.
• typescript/prefer-readonly-property — Disallows writable properties.
• typescript/prefer-readonly-set — Disallows writable sets.
• typescript/require-prop-type-annotation — Requires type annotation for class properties.
• typescript/require-this-void — Requires "this: void" for static methods.

Synonyms

You can use the same rule several times by adding synonym:

// .eslintrc.synonyms.js
module.exports = [
  "misc/wrap/class-methods-use-this",
  "misc/wrap/no-shadow"
];

// .eslintrc.js
module.exports = {
  rules: {
    // Same as ESLint core rule, but suppresses warnings for methods that have "this" parameter.
    "misc/wrap/class-methods-use-this": [
      "error",
      {
        plugin: "eslint",
        rule: "class-methods-use-this",
        skip: "FunctionExpression[params.0.name=this]"
      }
    ],
    // Same as typescript-eslint rule, but suppresses warnings for enums.
    "misc/wrap/no-shadow": [
      "error",
      {
        plugin: "@typescript-eslint/eslint-plugin",
        rule: "no-shadow",
        skip: "TSEnumDeclaration *"
      }
    ]
  }
};

Custom checks

Many custom checks can be created without writing full-fledged ESLint plugin. Use the rules below to create custom checks or adapt existing third-party rules:

• no-restricted-syntax — Disallows AST syntax (an extended version of ESLint core rule).
• require-syntax — Requires AST syntax.
• wrap — Wraps and modifies third-party rule.
• typescript/no-restricted-syntax — Disallows AST syntax with additional type check.

If you want to apply one rule several times (e.g. restrict several syntaxes), use rule synonyms.

Planned rules

• boolean-in-boolean-context — Require strict boolean type in boolean contexts like x && y or !x.
• consistent-import-as — Require that y in import { x as y } statement is from allowed list.
• consistent-test-file-name — Require that test file name matches some source file name.
• no-re-export-mixing — Require that file contains either only re-export or only export of new items.
• escape-doc-comment-entities — Require that "<" and ">" symbols inside doc comments are properly escaped.
• no-array-mutation — Forbid array mutation.
• no-duplicate-import — Forbid combining import { x } from "source" and import { x as y } from "source" in the same file.
• protected-rules — Do not allow to disable selected ESLint rules.
• sort-eslint-comments — Sort rules in eslint-disable comments.
• sort-switch-cases — Sort switch cases.
• spell-check — Spell check with international language support based on hunspell spell checker.