oxlint-complexity-line-rules

Purpose

Does oxlint support cyclomatic/cognitive complexity checks or max line length rules?

Key Findings

• max-len (line length): Built into oxlint core — enabled via config
• max-lines and max-lines-per-function: Built into oxlint core
• Cyclomatic/Cognitive complexity: NOT in oxlint core — use the community plugin oxlint-plugin-complexity

Built-in Rules (Oxlint Core)

eslint/max-len — Max Line Length

Enforces a maximum line length. Added to oxlint in April 2024.

Config (oxlintrc.json):

{
  "rules": {
    "max-len": ["error", {
      "code": 100,
      "ignoreUrls": true,
      "ignoreStrings": false,
      "ignoreTemplateLiterals": false,
      "ignoreRegExpLiterals": false,
      "ignoreComments": false,
      "ignoreTrailingComments": false,
      "ignorePattern": ""
    }]
  }
}

Note: JSX comment handling has limitations in the current AST.

Docs: https://oxc.rs/docs/guide/usage/linter/rules/eslint/max-len

eslint/max-lines — Max Lines Per File

Enforces a maximum number of lines per file.

eslint/max-lines-per-function — Max Lines Per Function

Enforces a maximum number of lines within a function (default: 50).

Config:

{
  "rules": {
    "max-lines-per-function": ["error", {
      "max": 50,
      "skipBlankLines": false,
      "skipComments": false,
      "IIFEs": false
    }]
  }
}

Docs: https://oxc.rs/docs/guide/usage/linter/rules/eslint/max-lines-per-function

Community Plugin: oxlint-plugin-complexity

For cyclomatic and cognitive complexity, use the third-party plugin:

Install:

npm install oxlint-plugin-complexity --save-dev

Config (oxlintrc.json):

{
  "jsPlugins": ["oxlint-plugin-complexity"],
  "rules": {
    "complexity/complexity": ["error", {
      "cyclomatic": 20,
      "cognitive": 15,
      "minLines": 10,
      "enableExtraction": true,
      "nestingTipThreshold": 3,
      "elseIfChainThreshold": 4,
      "logicalOperatorThreshold": 3
    }]
  }
}

Cyclomatic Complexity

Counts decision points (+1 for each): if, for, for...in, for...of, while, do...while, case, catch, ? :, &&, ||, ??

Cognitive Complexity

Penalizes nesting depth to measure understandability. Excludes React components and default value patterns like a || [].

Plugin Options

Supports: .js, .mjs, .cjs, .ts, .tsx, .jsx, .vue (extracts <script> blocks)

Plugin repo: https://github.com/itaymendel/oxlint-plugin-complexity

Summary Table

Sources

1. oxlint rules: eslint/max-len
2. oxlint rules: eslint/max-lines-per-function
3. oxlint rules: eslint/max-lines
4. oxlint-plugin-complexity GitHub
5. PR #2874: feat(linter): eslint/max-len