By name: jscpd description: Copy-paste detector for 220+ languages. Detect duplicated code and measure duplication percentages.
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
| Option | Description |
|---|---|
--reporters ai |
Use the AI-optimized reporter (compact clone list for agents) |
--reporters html |
Generate HTML report |
--reporters json |
Output JSON report |
--min-tokens N |
Minimum tokens to consider a duplication (default: 50) |
--min-lines N |
Minimum lines to consider a duplication (default: 5) |
--min-similarity N |
Minimum similarity percentage (default: 100, range: 1-100) |
--threshold N |
Exit with error if duplication % exceeds N |
--ignore "glob" |
Ignore patterns (comma-separated) |
--format "list" |
Limit to specific languages (e.g. typescript,javascript) |
--pattern "glob" |
Glob pattern to select files |
--gitignore |
Respect .gitignore |
--output "path" |
Directory to write reports to |
--silent |
Suppress output (useful with --output only) |
--list-output |
Print clone list to stdout (alternative to ai reporter) |
--store-path "path" |
Directory for LevelDB cache |
--no-tips |
Disable tips in output (enabled by default in CI) |
--config "path" |
Path to .jscpd.json config file |
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