Dead Code

ID: dead_code | Severity: Low (default)

Dead code refers to exported functions, classes, or variables that are not imported or used anywhere else in the project.

Why this is a smell

• Maintenance Burden: Developers might spend time updating or refactoring code that isn't even used.
• Bundle Size: Increases the final application size (though many bundlers do tree-shaking).
• Confusion: Makes the API of a module appear larger and more complex than it actually is.

Examples

Bad

// utils.ts
export const usedHelper = () => { ... };
export const unusedHelper = () => { ... }; // Reported as dead code

// main.ts
import { usedHelper } from './utils';

How to fix

1. Delete it: If it's truly unused, the best action is removal.
2. Mark as Entry Point: If it's part of a public API or a dynamic import, add it to entry_points in your config.

Configuration

# Rule-specific options
rules:
  dead_code:
    exclude:
      - '**/tests/**'
      - '**/temp/**'

# Global options (root level)
entry_points:
  - 'src/index.ts'
  - 'src/api/**/*.ts'

Options

Rule Options (rules.dead_code)

• exclude: A list of glob patterns to ignore when detecting dead code. Files matching these patterns will be treated as if they don't exist for the purpose of incoming dependency analysis.

Global Options (root level)

• entry_points: Global entry points that should never be reported as dead code.

ESLint Rule

This detector is available as an ESLint rule for real-time feedback in your editor.

// eslint.config.js
export default [
  {
    rules: {
      '@archlinter/no-dead-code': 'warn',
    },
  },
];

See ESLint Integration for setup instructions.