Configuration

Configuration File

Create a .jscpd.json file in your project root to configure jscpd:

{
  "threshold": 0,
  "reporters": ["html", "console"],
  "ignore": ["**/__snapshots__/**", "**/node_modules/**"],
  "absolute": true,
  "minLines": 5,
  "minTokens": 50
}

CLI Options

Examples

Basic scan

jscpd ./src

With pattern matching

jscpd --pattern "**/*.ts" ./src

Multiple reporters

jscpd --reporters html,json,console ./src

Custom threshold

Fail if duplication exceeds 5%:

jscpd --threshold 5 ./src

Ignore specific patterns

jscpd --ignore "**/*.test.ts,**/__mocks__/**" ./src

Skip comments (weak mode)

Use --skipComments as a shorthand for --mode weak:

jscpd --skipComments ./src

Map filenames to formats

For extensionless files like Makefile and Dockerfile:

jscpd --formats-names "makefile:Makefile,GNUmakefile;docker:Dockerfile" ./src

Custom LevelDB cache path

When running multiple jscpd processes in parallel:

jscpd --store leveldb --store-path /tmp/jscpd-cache ./src

Suppress tips in CI

Tips are automatically suppressed when --silent is active. To suppress manually:

jscpd --noTips ./src

Show debug information

jscpd --debug ./src

Show full information during detection

jscpd --verbose ./src

Cross-folder detection only

jscpd --skipLocal /path/to/folder1/ /path/to/folder2/

Ignore case in code

jscpd --ignoreCase ./src

Don't follow symlinks

jscpd --noSymlinks ./src

Ignore blocks by regexp pattern

jscpd --ignore-pattern "import.*from\s*'.*'" ./src

Package.json Configuration

You can also configure jscpd in your package.json:

{
  "jscpd": {
    "threshold": 0,
    "reporters": ["html", "console"],
    "ignore": ["**/node_modules/**"],
    "absolute": true,
    "gitignore": true
  }
}

Modes

The --mode option controls detection quality:

• strict — use all types of symbols as token, skip only blocks marked as ignored
• mild — skip blocks marked as ignored and new lines and empty symbols (default)
• weak — skip blocks marked as ignored and new lines and empty symbols and comments

Cross-Format Detection

jscpd v4.2+ supports cross-format detection for multi-block file types:

• Vue SFC (.vue) — <script>, <template>, <style> blocks tokenized separately
• Svelte (.svelte) — script and style blocks tokenized independently
• Astro (.astro) — frontmatter and template sections tokenized independently
• Markdown (.md) — fenced code blocks tokenized by language

This means a <script> block in a .vue file can be matched against a .ts file, and a fenced Python code block in Markdown can match a .py file.

Breaking Change for Vue Users

Vue files are no longer tokenized as markup. Each block uses its resolved sub-format (javascript, typescript, css, scss, etc.). Any tooling that relied on .vue clones being reported under markup must be updated.

Shebang Detection

jscpd can detect duplications in script files that have no file extension by reading the #! shebang line:

Both direct (#!/usr/bin/bash) and env-mediated (#!/usr/bin/env python3) shebangs are supported. Version suffixes are stripped automatically (python3.11 → python).

Ignored Blocks

Mark blocks in code as ignored:

/* jscpd:ignore-start */
import lodash from 'lodash';
import React from 'react';
import {User} from './models';
import {UserService} from './services';
/* jscpd:ignore-end */

<!--
// jscpd:ignore-start
-->
<meta data-react-helmet="true" name="theme-color" content="#cb3837"/>
<link data-react-helmet="true" rel="stylesheet" href="https://static.npmjs.com/103af5b8a2b3c971cba419755f3a67bc.css"/>
<!--
// jscpd:ignore-end
-->