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Javascript

The Best Way to Generate PDF from HTML Using PDF-lib

Marcelo Abreu, Founder of pdforge, picture

Marcelo | Founder

Oct 3, 2024

An Introduction to the JavaScript PDF Generation Library: PDF-lib

If you're looking for a way to generate PDFs in your Node.js project, PDF-lib is a lightweight, JavaScript-based library that might catch your attention. However, before you dive in, it's essential to assess whether its capabilities align with your needs, especially when working with HTML to PDF conversions for SaaS reports.

You can check our the full documentation here.

Alternative PDF Libraries: How PDF-lib Compares to Other Tools

While PDF-lib offers a simple, JavaScript-based solution for PDF creation, it does come with limitations.

npm trend print for pdf generation javascript libraries

For one, it hasn’t been updated in over three years, according to npm, which raises concerns about long-term support and security. You should tread cautiously when incorporating it into production environments. Alternatives like Puppeteer or Playwright offer more feature-rich, modern support, leveraging browser engines for precise HTML rendering. Though these tools can be more resource-intensive, they ensure better HTML to PDF conversions. PDF-lib’s strength lies in its control and customization but lacks the robust, out-of-the-box HTML rendering you might need for complex layouts.

Getting Started with PDF-lib: Setting Up Your Node.js Environment

To get started with PDF-lib, first install it using npm:

npm install pdf-lib

Import the library and start with a basic example:

const { PDFDocument } = require('pdf-lib');
const pdfDoc = await PDFDocument.create();
const page = pdfDoc.addPage([600, 400]);
page.drawText('Hello World');
const pdfBytes = await pdfDoc.save();

This setup demonstrates how easy it is to create a basic PDF using PDF-lib. However, for developers looking to convert HTML to PDF, the manual process of rendering HTML elements individually will quickly become cumbersome, especially when dealing with complex layouts.

Key Features of PDF-lib for Developers

PDF-lib’s API is designed with developers in mind, offering intuitive methods for manipulating PDFs. Some of the core capabilities include:

1. Creating a new PDF document:

const pdfDoc = await PDFDocument.create();
const page = pdfDoc.addPage([600, 400]);
page.drawText('Hello World');
const pdfBytes = await pdfDoc.save();

2. Modifying existing PDFs:

const existingPdf = await fetch('path/to/existing.pdf').then(res => res.arrayBuffer());
const pdfDoc = await PDFDocument.load(existingPdf);
const pages = pdfDoc.getPages();
pages[0].drawText('Modified Text');
const pdfBytes = await pdfDoc.save();

Converting HTML to PDF: Practical Implementation with PDF-lib

While PDF-lib doesn't directly parse HTML, you can manually map HTML content into its PDF creation methods. For example, if you're generating an invoice, you can create an HTML template and extract the necessary content to render it in your PDF:

<!DOCTYPE html>
<html>
<head>
  <style>
    .invoice { width: 600px; margin: 0 auto; }
    .header { background-color: #f2f2f2; padding: 10px; text-align: center; }
    .details { padding: 10px; }
  </style>
</head>
<body>
  <div class="invoice">
    <div class="header">
      <h1>Invoice</h1>
    </div>
    <div class="details">
      <p>Client: John Doe</p>
      <p>Total: $500</p>
    </div>
  </div>
</body>
</html>

To replicate this in PDF-lib, you'd need to manually position each element:

page.drawText('Invoice for John Doe', { x: 50, y: 700 });
page.drawText('Total: $500', { x: 50, y: 650 });

This approach works for simple layouts but requires meticulous handling for more complex HTML structures.

Advanced Techniques: Enhancing PDF Reports with PDF-lib

If you're looking to add more functionality to your PDFs, PDF-lib allows for embedding images and fonts, enabling a more customized PDF generation. For example, embedding an image:

const imageBytes = await fetch('path/to/image.png').then(res => res.arrayBuffer());
const image = await pdfDoc.embedPng(imageBytes);
page.drawImage(image, { x: 50, y: 500 });

Integrating with a PDF API

For SaaS platforms, automating PDF generation at scale might require offloading the heavy lifting to a PDF API. By integrating APIs like pdforge you can handle high-volume PDF generation, complex formatting, and post-processing, all from a single backend call.

fetch('https://api.pdforge.com/v1/pdf/sync', {
  method: 'POST',
  body: JSON.stringify({ templateId: 'your-template' , data: {html:'your-html' } }),
  headers: { 'Authorization' : 'Bearer your-api-key' }
});

These APIs handle HTML to PDF conversion more efficiently than jsPDF for large-scale, complex use cases.

Conclusion

While PDF-lib is lightweight and offers a high level of control, its lack of updates over the past few years and low-level API may not make it the best fit for more advanced HTML to PDF use cases.

For developers seeking a more seamless solution, modern libraries like Playwright or Puppeteer provide better HTML rendering capabilities. Alternatively, third-party APIs like pdforge offer robust PDF generation without the need to manage the intricacies of low-level PDF manipulation.