PDF Manipulation with pdf-lib

pdf-lib is a powerful library for creating and modifying PDF documents in JavaScript and TypeScript.

Capabilities

Document Creation

• Create PDFs from scratch
• Add pages, text, images, and forms
• Full control over layout and styling

Document Modification

• Merge multiple PDFs
• Split PDFs into separate files
• Add metadata (title, author, subject)
• Extract and modify pages

Use Cases in The Workbench

PDF Merger

Combine multiple PDF files into a single document:

import { PDFDocument } from 'pdf-lib';

const mergedPdf = await PDFDocument.create();
for (const pdfBytes of pdfFiles) {
  const pdf = await PDFDocument.load(pdfBytes);
  const pages = await mergedPdf.copyPages(pdf, pdf.getPageIndices());
  pages.forEach((page) => mergedPdf.addPage(page));
}

PDF Splitter

Extract specific page ranges:

const sourcePdf = await PDFDocument.load(pdfBytes);
const newPdf = await PDFDocument.create();
const pages = await newPdf.copyPages(sourcePdf, [0, 1, 2]); // Pages 1-3
pages.forEach((page) => newPdf.addPage(page));

Metadata Management

Add or modify PDF metadata:

const pdfDoc = await PDFDocument.load(pdfBytes);
pdfDoc.setTitle('My Document');
pdfDoc.setAuthor('The Workbench');
pdfDoc.setSubject('Generated PDF');
pdfDoc.setProducer('The Workbench PDF Service');

Benefits

1. Pure JavaScript: No native dependencies
2. TypeScript Support: Full type definitions
3. Browser Compatible: Works in both Node.js and browsers
4. Small Bundle: Lightweight library

Performance Tips

• Load PDFs once and reuse
• Use copyPages for better performance than individual page copying
• Stream large files when possible
• Cache frequently used PDFs