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This repository containseslint-plugin-sonarjs up to version^1.0.0. For versions>=2.0.0 please go to the repository of theSonarJS analyzer. The new versions ofeslint-plugin-sonarjs makes all SonarJS rules available for ESLint users, instead of a subset as it was with^1.0.0 living here.

No new changes are expected to land here.

SonarJS rules for ESLint to help developers produceClean Code by detecting bugs and suspicious patterns.

Rules in this category aim to find places in code that have a high chance of being bugs, i.e. don't work as intended.

• All branches in a conditional structure should not have exactly the same implementation (no-all-duplicated-branches)
• Collection elements should not be replaced unconditionally (no-element-overwrite)
• Empty collections should not be accessed or iterated (no-empty-collection)
• Function calls should not pass extra arguments (no-extra-arguments)
• Related "if/else if" statements should not have the same condition (no-identical-conditions)
• Identical expressions should not be used on both sides of a binary operator (no-identical-expressions)
• Return values from functions without side effects should not be ignored (no-ignored-return) (uses-types)
• Loops with at most one iteration should be refactored (no-one-iteration-loop)
• The output of functions that don't return anything should not be used (no-use-of-empty-return-value)
• Non-existent operators '=+', '=-' and '=!' should not be used (non-existent-operator) (:wrench:fixable)

Code Smells, or maintainability issues, are raised for places of code which might be costly to change in the future. These rules also help to keep the high code quality and readability. And finally, some rules report issues on different suspicious code patterns.

• Cognitive Complexity of functions should not be too high (cognitive-complexity)
• "if ... else if" constructs should end with "else" clauses (elseif-without-else) (disabled)
• "switch" statements should not have too many "case" clauses (max-switch-cases)
• Collapsible "if" statements should be merged (no-collapsible-if)
• Collection sizes and array length comparisons should make sense (no-collection-size-mischeck) (:wrench:fixable,uses-types)
• String literals should not be duplicated (no-duplicate-string)
• Two branches in a conditional structure should not have exactly the same implementation (no-duplicated-branches)
• Boolean expressions should not be gratuitous (no-gratuitous-expressions)
• Functions should not have identical implementations (no-identical-functions)
• Boolean checks should not be inverted (no-inverted-boolean-check) (:wrench:fixable,disabled)
• "switch" statements should not be nested (no-nested-switch)
• Template literals should not be nested (no-nested-template-literals)
• Boolean literals should not be redundant (no-redundant-boolean)
• Jump statements should not be redundant (no-redundant-jump) (:wrench:fixable)
• Conditionals should start on new lines (no-same-line-conditional) (:wrench:fixable)
• "switch" statements should have at least 3 "case" clauses (no-small-switch)
• Collection and array contents should be used (no-unused-collection)
• "catch" clauses should do more than rethrow (no-useless-catch)
• Local variables should not be declared and then immediately returned or thrown (prefer-immediate-return) (:wrench:fixable)
• Object literal syntax should be used (prefer-object-literal)
• Return of boolean expressions should not be wrapped into an "if-then-else" statement (prefer-single-boolean-return) (:wrench:fixable)
• A "while" loop should be used instead of a "for" loop (prefer-while) (:wrench:fixable)

• Node.js (>=16.x).
• ESLint 8.x or 9.x (peer dependency for the plugin).

• If you don't have ESLint yet configured for your project, followthese instructions.
• Installeslint-plugin-sonarjs usingnpm (oryarn) for your project or globally:

npm install eslint-plugin-sonarjs --save-dev# install for your projectnpm install eslint-plugin-sonarjs -g# or install globally

• Addeslint-plugin-sonarjs to the plugins of your ESLint config.

For ESLint 9: addplugins option to youreslint.config.js and include the recommended config to enable all rules:

import sonarjs from "eslint-plugin-sonarjs";[  sonarjs.configs.recommended,  {    "plugins": {      sonarjs,    }  }]

For ESLint 8: addplugins option to your.eslintrc andplugin:sonarjs/recommended-legacy to theextends option to enable all recommended rules:

{"plugins": ["sonarjs"],"extends": ["plugin:sonarjs/recommended-legacy"]}

• or enable only some rules manually:

{"rules": {"sonarjs/cognitive-complexity":"error","sonarjs/no-identical-expressions":"error"// etc.  }}

• To allow each of the rules to fully perform, use@typescript-eslint/parser as a parser for ESLint (like we do) and set theparserOptions.project option. Thanks to it, type information is available, which is beneficial or even essential for some rules.

This plugin provides only arecommended configuration. Almost all rules are activated in this profile with a few exceptions (check thedisabled tag in the rules list). Therecommended configuration activates rules witherror severity.We include arecommended-legacy configuration to be backward compatible with ESLint v8, with the same rule configuration..

This plugin exposes to ESLint users a subset of JS/TS rules from Sonar-* products (akaSonarJS). We extracted the rules that are not available in ESLint core or other ESLint plugins to be beneficial for the ESLint community.

If you are aSonarQube orSonarCloud user, to lint your code locally, we suggest usingSonarLint IDE extension (available for VSCode, JetBrains IDEs and Eclipse). You can connect SonarLint to your SonarQube/SonarCloud project to synchronize rules configuration, issue statuses, etc.

Do you want to participate in the development of the project? Have a look at ourcontributing guide!