dead-code-elimination

name	dead-code-elimination
description	Identification and removal of unused code, imports, and unreachable branches.
category	refactoring
version	1

Dead Code Elimination

Purpose

Remove code that provides no value and increases maintenance burden.

Detection Methods

Automated Detection

# TypeScript unused
npx ts-unused-exports --project tsconfig.json

# ESLint unused vars
eslint --rule "no-unused-vars: error"

# Unimported files
npx unimported

Manual Detection

• Functions never called
• Variables assigned but never read
• Imports not used
• Props passed but ignored
• Branches never executed

Common Patterns

1. Unused Exports

// BAD
export const unusedHelper = () => {}

// GOOD
// Delete the function

2. Unused Imports

// BAD
import { unused } from './utils'

// GOOD  
import { used } from './utils'

3. Commented Code

// BAD
// const oldLogic = () => {}

// GOOD
// Delete it - git has history

4. Type-only Imports

// BAD
import { type User } from './types'
function processUser(user: User) {}

// GOOD
import type { User } from './types'

Safety Rules

1. Verify with TypeScript strict mode
2. Run tests after removal
3. Check across all entry points
4. Consider external consumers