Document Page Counter

A TypeScript library for counting pages in PDF and DOCX documents with multiple fallback strategies.

Features

• PDF Support: Uses pdf-lib to extract exact page count from PDF metadata
• DOCX Support: Extracts page count from document properties or estimates from word count
• Fallback Strategies: Multiple methods to ensure you always get a page count
• Next.js Integration: Pre-built API route handlers
• TypeScript: Full type safety and IntelliSense support
• Configurable: Customize heuristics for different document types

Installation

npm install document-page-counter

Quick Start

Basic Usage

import { countDocumentPages } from 'document-page-counter';

// From a File object
const file = document.getElementById('fileInput').files[0];
const buffer = await file.arrayBuffer();
const result = await countDocumentPages(buffer, file.type);

console.log(`Document has ${result.pages} pages (method: ${result.method})`);

Class-based Usage

import { DocumentPageCounter } from 'document-page-counter';

const counter = new DocumentPageCounter({
  wordsPerPage: 300, // Custom words per page estimate
  pdfBytesPerPage: 50000, // Custom PDF size heuristic
  docxBytesPerPage: 20000 // Custom DOCX size heuristic
});

const result = await counter.countPagesFromFile(file);

Next.js API Routes

Option 1: Use the pre-built handler

// app/api/count-pages/route.ts
import { createPageCountHandler } from 'document-page-counter';

export const POST = createPageCountHandler({
  wordsPerPage: 250
});

Option 2: Manual integration

// app/api/count-pages/route.ts
import { NextResponse } from 'next/server';
import { countDocumentPages } from 'document-page-counter';

export async function POST(request: Request) {
  const formData = await request.formData();
  const file = formData.get('file') as File;
  
  if (!file) {
    return NextResponse.json({ error: 'No file provided' }, { status: 400 });
  }

  try {
    const buffer = await file.arrayBuffer();
    const result = await countDocumentPages(buffer, file.type);
    
    return NextResponse.json({ 
      pages: result.pages,
      method: result.method 
    });
  } catch (error) {
    return NextResponse.json({ 
      error: 'Failed to count pages' 
    }, { status: 500 });
  }
}

API Reference

countDocumentPages(buffer, mimeType, options?)

Count pages in a document buffer.

Parameters:

• buffer: ArrayBuffer - The document buffer
• mimeType: string - MIME type ('application/pdf' or 'application/vnd.openxmlformats-officedocument.wordprocessingml.document')
• options?: PageCountOptions - Configuration options

Returns: Promise<PageCountResult>

DocumentPageCounter

Class for counting pages with configurable options.

Constructor Options:

• wordsPerPage?: number - Words per page for DOCX estimation (default: 250)
• pdfBytesPerPage?: number - Bytes per page for PDF size estimation (default: 40,000)
• docxBytesPerPage?: number - Bytes per page for DOCX size estimation (default: 15,000)

Methods:

• countPages(buffer, mimeType) - Count pages from buffer
• countPagesFromFile(file) - Count pages from File object
• countPdfPages(buffer) - Count PDF pages specifically
• countDocxPages(buffer) - Count DOCX pages specifically

PageCountResult

interface PageCountResult {
  pages: number;
  method: 'metadata' | 'heuristic' | 'word-count';
}

• metadata: Extracted from document properties (most accurate)
• word-count: Estimated from word count (DOCX fallback)
• heuristic: Estimated from file size (last resort)

Supported File Types

• PDF: application/pdf
• DOCX: application/vnd.openxmlformats-officedocument.wordprocessingml.document

Error Handling

The library uses fallback strategies to ensure you always get a page count:

1. PDF: Try to parse with pdf-lib → fallback to size estimation
2. DOCX: Try document properties → word count estimation → size estimation

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

MIT License - see the LICENSE file for details.

Dependencies

• jszip - For reading DOCX files
• fast-xml-parser - For parsing XML in DOCX files
• mammoth - For extracting text from DOCX files
• pdf-lib - For reading PDF files