jscpd

Copy-paste detector for programming source code, supports 220+ 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>

# Second pass, noisier: copies that only differ in names and values (Type-2, "renamed").
# Review each hit before acting on it.
npx jscpd --reporters ai --ignore-identifiers --min-tokens 70 <path>

# Third pass, noisier still: copies with a few edited lines or the same function
# structure (Type-3, "similar"). Keep the settings tight.
npx jscpd --reporters ai --max-gap-lines 1 --similarity <path>

# Where to refactor first: clone list plus a hotspot summary
npx jscpd --reporters ai --summary <path>

# Most complex files only, without clone detection
npx jscpd --complexity --reporters ai <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
src/cart/ basket.js:1-9 ~ cart.js:1-9 (renamed)
src/api/ save-account.js:1-12 ~ save-user.js:1-11 [~0.91 gap]
src/billing/ orders.ts:1-14 ~ refunds.ts:1-15 [~0.85 ast]
---
5 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