Jscpd

jscpd

Copy-paste detector for programming source code, supports 150+ languages. Use this skill to run jscpd and understand its output.

Quick Start

# Run with ai reporter (compact output optimized for agents)
npx jscpd --reporters ai <path>

# With ignore patterns
npx jscpd --reporters ai --ignore "**/node_modules/**,**/dist/**" <path>

# Scope to specific formats
npx jscpd --reporters ai --format "javascript,typescript" <path>

AI Reporter Output Format

The ai reporter produces compact, token-efficient output designed for agent consumption:

Clones:
src/ foo.ts:10-25 ~ bar.ts:42-57
src/utils/helpers.ts:100-120 ~ src/utils/other.ts:5-25
---
3 clones · 4.2% duplication

Each line represents one clone pair:

• Same file: path/file.ts 10-25 ~ 45-60 (shared path shown once)
• Same directory: shared/prefix/ file-a.ts:10-25 ~ file-b.ts:42-57 (common prefix factored out)
• Different paths: path/a.ts:10-25 ~ path/b.ts:42-57

Options

Configuration File

Create a .jscpd.json in your project root:

{
  "threshold": 0,
  "reporters": ["ai"],
  "ignore": ["**/node_modules/**", "**/dist/**", "**/*.min.*"],
  "format": ["typescript", "javascript"],
  "minLines": 5,
  "minTokens": 50,
  "output": "./reports/jscpd"
}

Refactoring Duplicated Code

Once you've detected clones, use the dry-refactoring skill for a guided workflow to eliminate them:

→ dry-refactoring — step-by-step refactoring strategies and workflow for removing duplication. Install with:

  npx skills add https://github.com/kucherenko/jscpd --skill dry-refactoring