epubcheck-ts

A TypeScript port of EPUBCheck - the official conformance checker for EPUB publications.

Note: This library is primarily developed for internal use at 3ook.com and is built with AI-assisted development. While it has comprehensive test coverage (208 tests) and ~65% feature parity with Java EPUBCheck, it may not be suitable for mission-critical production workloads. For production environments requiring full EPUB validation, consider using the official Java EPUBCheck. Contributions and feedback are welcome!

Features

• CLI and programmatic API: Use as a command-line tool or integrate into your application
• Cross-platform: Works in Node.js (18+) and modern browsers
• Partial EPUB validation: Currently ~65% of EPUBCheck feature parity
• Zero native dependencies: Pure JavaScript/WebAssembly, no compilation required
• TypeScript first: Full type definitions included
• Tree-shakable: ESM with proper exports for optimal bundling

Try it Online

Try the live demo at likecoin.github.io/epubcheck-ts - validate your EPUB files directly in the browser without uploading to any server.

Installation

npm install @likecoin/epubcheck-ts

Quick Start

Command Line Interface (CLI)

Quick validation:

npx @likecoin/epubcheck-ts book.epub

Or install globally:

npm install -g @likecoin/epubcheck-ts
epubcheck-ts book.epub

CLI Options:

epubcheck-ts <file.epub> [options]

Options:
  -j, --json <file>        Output JSON report to file (use '-' for stdout)
  -q, --quiet              Suppress console output (errors only)
  -p, --profile <name>     Validation profile (default|dict|edupub|idx|preview)
  -w, --fail-on-warnings   Exit with code 1 if warnings are found
  -v, --version            Show version information
  -h, --help               Show this help message

Examples:

# Basic validation
epubcheck-ts book.epub

# Generate JSON report
epubcheck-ts book.epub --json report.json

# Quiet mode for CI/CD
epubcheck-ts book.epub --quiet --fail-on-warnings

# Validate with specific profile
epubcheck-ts dictionary.epub --profile dict

Note: This CLI provides ~65% coverage of Java EPUBCheck features. For complete EPUB 3 conformance testing, use the official Java EPUBCheck.

ES Modules (recommended)

import { EpubCheck } from '@likecoin/epubcheck-ts';
import { readFile } from 'node:fs/promises';

// Load EPUB file
const epubData = await readFile('book.epub');

// Validate
const result = await EpubCheck.validate(epubData);

if (result.valid) {
  console.log('EPUB is valid!');
} else {
  console.log(`Found ${result.errorCount} errors and ${result.warningCount} warnings`);
  
  for (const message of result.messages) {
    console.log(`${message.severity}: ${message.message}`);
    if (message.location) {
      console.log(`  at ${message.location.path}:${message.location.line}`);
    }
  }
}

CommonJS

const fs = require('node:fs');

async function validate() {
  const { EpubCheck } = await import('epubcheck-ts');
  
  const epubData = fs.readFileSync('book.epub');
  const result = await EpubCheck.validate(epubData);
  
  console.log(result.valid ? 'Valid!' : 'Invalid');
}

validate();

Browser

import { EpubCheck } from '@likecoin/epubcheck-ts';

// From file input
const fileInput = document.querySelector('input[type="file"]');
fileInput.addEventListener('change', async (event) => {
  const file = event.target.files[0];
  const data = new Uint8Array(await file.arrayBuffer());
  
  const result = await EpubCheck.validate(data);
  console.log(result);
});

API

EpubCheck.validate(data, options?)

Static method to validate an EPUB file.

Parameters:

• data: Uint8Array - The EPUB file contents
• options?: EpubCheckOptions - Optional validation options

Returns: Promise<EpubCheckResult>

new EpubCheck(options?)

Create a reusable validator instance.

const checker = new EpubCheck({
  version: '3.3',
  profile: 'default',
  locale: 'en',
});

const result1 = await checker.check(epub1Data);
const result2 = await checker.check(epub2Data);

Options

interface EpubCheckOptions {
  /** EPUB version to validate against (auto-detected if not specified) */
  version?: '2.0' | '3.0' | '3.1' | '3.2' | '3.3';
  
  /** Validation profile */
  profile?: 'default' | 'edupub' | 'idx' | 'dict' | 'preview';
  
  /** Include usage messages in results (default: false) */
  includeUsage?: boolean;
  
  /** Include info messages in results (default: true) */
  includeInfo?: boolean;
  
  /** Maximum errors before stopping, 0 = unlimited (default: 0) */
  maxErrors?: number;
  
  /** Locale for messages (default: 'en') */
  locale?: string;
}

Result

interface EpubCheckResult {
  /** Whether the EPUB is valid (no errors or fatal errors) */
  valid: boolean;
  
  /** All validation messages */
  messages: ValidationMessage[];
  
  /** Counts by severity */
  fatalCount: number;
  errorCount: number;
  warningCount: number;
  infoCount: number;
  usageCount: number;
  
  /** Detected EPUB version */
  version?: string;
  
  /** Validation time in milliseconds */
  elapsedMs: number;
}

interface ValidationMessage {
  /** Unique message identifier (e.g., 'OPF-001') */
  id: string;
  
  /** Severity level */
  severity: 'fatal' | 'error' | 'warning' | 'info' | 'usage';
  
  /** Human-readable message */
  message: string;
  
  /** Location in the EPUB */
  location?: {
    path: string;
    line?: number;
    column?: number;
    context?: string;
  };
  
  /** Suggestion for fixing the issue */
  suggestion?: string;
}

JSON Report

Generate a JSON report compatible with the original EPUBCheck:

import { EpubCheck, Report } from '@likecoin/epubcheck-ts';

const result = await EpubCheck.validate(data);
const jsonReport = Report.toJSON(result);
console.log(jsonReport);

Supported Environments

| Environment | Version | Notes | |-------------|---------|-------| | Node.js | 18+ | Full support | | Chrome | 89+ | Full support | | Firefox | 89+ | Full support | | Safari | 15+ | Full support | | Edge | 89+ | Full support |

Architecture

This library is a TypeScript port of the Java-based EPUBCheck tool maintained by the W3C. Key implementation details:

• XML Processing: Uses libxml2-wasm for XML parsing and schema validation (RelaxNG, XSD) via WebAssembly
• ZIP Handling: Uses fflate for fast, lightweight EPUB container processing
• CSS Validation: Uses css-tree for CSS parsing and validation
• Schematron: Uses fontoxpath with slimdom for XPath 3.1 evaluation

Validation Coverage

| Component | Status | Completeness | Notes | |-----------|--------|--------------|-------| | OCF Container | 🟡 Partial | ~70% | ZIP structure, mimetype (uncompressed check), container.xml | | Package Document (OPF) | 🟡 Partial | ~70% | Metadata, manifest, spine, collections, version/date validation | | Content Documents | 🟡 Partial | ~70% | XHTML structure, script/MathML/SVG detection, link validation | | Navigation Document | 🟡 Partial | ~40% | Nav structure, NCX validation, remote link validation | | Schema Validation | 🟡 Partial | ~70% | RelaxNG, XSD, Schematron working | | CSS | 🟡 Partial | ~50% | @font-face, @import, media overlay classes, position warnings | | Cross-reference Validation | 🟡 Partial | ~75% | Reference tracking, fragment validation, undeclared resources | | Accessibility Checks | 🟡 Partial | ~75% | Empty links, image alt, SVG titles, MathML alttext | | Media Overlays | ❌ Not Started | 0% | Planned | | Media Validation | ❌ Not Started | 0% | Planned |

Legend: 🟢 Complete | 🟡 Partial | 🔴 Basic | ❌ Not Started

Overall Progress: ~65% of Java EPUBCheck features

See PROJECT_STATUS.md for detailed comparison.

Development

Prerequisites

• Node.js 18+
• npm 9+

Setup

# Clone the repository
git clone https://github.com/likecoin/epubcheck-ts.git
cd epubcheck-ts

# Install dependencies
npm install

# Run tests
npm test

# Build
npm run build

Scripts

| Script | Description | |--------|-------------| | npm run build | Build the library (ESM + CJS) | | npm run dev | Build in watch mode | | npm test | Run tests in watch mode | | npm run test:run | Run tests once | | npm run test:coverage | Run tests with coverage | | npm run lint | Lint with ESLint | | npm run lint:fix | Lint and auto-fix | | npm run format | Format with Biome | | npm run typecheck | TypeScript type checking | | npm run check | Run all checks (format + typecheck) |

Project Structure

epubcheck-ts/
├── src/
│   ├── index.ts           # Public API exports
│   ├── checker.ts         # Main EpubCheck class
│   ├── types.ts           # TypeScript type definitions
│   ├── core/              # Core validation logic
│   ├── ocf/               # OCF container validation ✅
│   ├── opf/               # Package document validation ✅
│   ├── content/           # Content document validation ✅
│   ├── nav/               # Navigation validation ✅
│   ├── ncx/               # NCX validation (EPUB 2) ✅
│   ├── references/        # Cross-reference validation ✅
│   ├── schema/            # Schema validation ✅
│   │   ├── relaxng.ts     # RelaxNG validation
│   │   ├── xsd.ts         # XSD validation
│   │   ├── schematron.ts  # Schematron validation
│   │   └── orchestrator.ts # Schema orchestration
│   └── messages/          # Error messages
├── schemas/               # Schema files (RNG, RNC, SCH)
├── test/
│   ├── fixtures/          # Test EPUB files
│   └── integration/       # Integration tests
├── examples/
│   └── web/               # Web demo ✅
└── dist/                  # Build output

Legend: ✅ Implemented

Comparison with Java EPUBCheck

| Aspect | epubcheck-ts | EPUBCheck (Java) | |--------|--------------|------------------| | Runtime | Node.js / Browser | JVM | | Feature Parity | ~65% | 100% | | Bundle Size | ~55KB JS + ~1.5MB WASM | ~15MB | | Installation | npm install | Download JAR | | Integration | Native JS/TS | CLI or Java API | | Performance | Comparable | Baseline |

Note: epubcheck-ts is currently in active development. See PROJECT_STATUS.md for detailed feature comparison.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md for guidelines.

For AI agents contributing to this project, see AGENTS.md.

License

GPL-3.0

This is an independent TypeScript implementation inspired by the Java-based EPUBCheck (BSD-3-Clause). No code was directly copied from the original project.

Acknowledgments

• W3C EPUBCheck - The original Java implementation
• DAISY Consortium - Maintainers of EPUBCheck
• libxml2-wasm - WebAssembly XML processing

Built by 3ook.com

This project is built and maintained by the 3ook.com team. 3ook is a Web3 eBook platform where authors can publish EPUB ebooks and readers can collect them as digital assets. If you're an author looking to publish your ebook, check out 3ook.com.

Related Projects

• EPUBCheck - Official Java validator
• epub.js - EPUB reader library
• r2-shared-js - Readium shared models