Salts

A TypeScript dead code detector that finds unused functions and methods using Babel AST analysis.

Features

• Detects unused functions, methods, and arrow functions
• Handles alias resolution (variable assignments, imports, exports)
• Supports JSX callback detection
• Optional React function component detection (--jsx-components)
• Tracks transitive usage through assignment chains
• Configurable export handling

Installation

npm install salts

From Source

npm install
npm run build

Usage

# Analyze a directory
npx salts ./src

# Include exported functions in the report
npx salts ./src --include-exports

# Count React component usage as function usage
npx salts ./src --jsx-components

# Ignore additional patterns
npx salts ./src --ignore "**/*.test.ts" --ignore "**/fixtures/**"

Options

| Option | Description | |--------|-------------| | --include-exports | Include exported functions in dead code report (by default, exports are considered "used") | | --jsx-components | Count JSX component usage (e.g., <MyComponent />) as function usage | | --ignore <patterns> | Additional glob patterns to exclude from analysis |

How It Works

What's Detected as a Function Declaration

• Named functions: function foo() {}
• Class methods: class X { method() {} }
• Arrow functions: const foo = () => {}
• Function expressions: const foo = function() {}

What Counts as Usage

A function is considered "used" if it is:

1. Called directly: myFunc()
2. Called as a method: obj.myFunc(), this.myFunc(), obj['myFunc']()
3. Passed as a callback: arr.map(myFunc)
4. Used in JSX: <Button onClick={myFunc} />
5. Assigned and the assignment is used: const x = myFunc; x()
6. Imported with alias: import { func as alias } where alias is used
7. Exported with alias: export { func as alias } where alias is used
8. Used as a JSX component: <MyComponent /> (requires --jsx-components flag)

Alias Resolution

Assignment chains are followed transitively:

const x = myFunc;
const y = x;
y(); // myFunc is marked as used

Default Ignored Patterns

• **/node_modules/**
• **/dist/**
• **/build/**
• **/*.d.ts
• **/.git/**

Development

# Build the project
npm run build

# Watch mode
npm run dev

# Run tests
npm test

# Run tests with coverage
npm run test:coverage

License

MIT