Efficiently Printing PDFs in JavaScript

Printing PDFs directly from a web browser using JavaScript isn’t straightforward due to browser inconsistencies and security considerations. However, several techniques can effectively trigger the browser’s print dialog for PDFs. This article explores two popular methods: leveraging an iframe and utilizing the Print.js library.

Table of Contents

• Printing PDFs with the iframe Tag
• Printing PDFs with the Print.js Library
• Choosing the Right Method

Printing PDFs with the iframe Tag

This approach is simple, requiring no external libraries. It embeds the PDF in an iframe, then triggers printing from the iframe’s context.

Implementation:

1. Embed the PDF: Use an <iframe> tag, setting its src attribute to the PDF’s URL and hiding it using CSS:

<iframe id="pdf-iframe" src="your-pdf-file.pdf" style="display: none;"></iframe>

2. Trigger Printing: Use JavaScript to access the iframe’s content window and call its print() method:

function printPdf() {
  const iframe = document.getElementById('pdf-iframe');
  if (iframe.contentWindow) { // Check if contentWindow exists to prevent errors
    iframe.contentWindow.focus(); // Ensure the iframe is focused before printing
    iframe.contentWindow.print();
  } else {
    console.error("Error: Could not access iframe content window.");
  }
}

3. Add a Print Button: Create a button that calls printPdf():

<button onclick="printPdf()">Print PDF</button>

Limitations:

• Browser Compatibility: Reliability varies across browsers. Some might require user interaction or specific permissions.
• Limited Control: Minimal control over page ranges or print settings.
• Security: Embedding PDFs directly might pose security risks depending on the PDF’s origin.

Printing PDFs with the Print.js Library

Print.js offers a more robust and feature-rich solution, handling browser inconsistencies and providing better control. It’s a lightweight library easily integrated into your project.

Implementation:

1. Include Print.js: Add the Print.js library to your HTML using a CDN:

<script src="https://cdnjs.cloudflare.com/ajax/libs/print.js/1.6.2/print.min.js"></script>

2. Trigger Printing: Use Print.js’s printJS() function:

function printPdf() {
  printJS({
    printable: 'your-pdf-file.pdf',
    type: 'pdf',
  });
}

3. Add a Print Button (same as before):

<button onclick="printPdf()">Print PDF</button>

Advantages:

• Improved Browser Compatibility: Effectively handles cross-browser differences.
• More Control: Offers some customization options compared to the iframe method.
• Easier to Use: A simpler and more intuitive API.

Choosing the Right Method

The iframe method is simpler but less reliable and provides less control. Print.js offers a more robust, feature-rich, and easier-to-use solution but requires adding an external library. The best choice depends on your project’s needs, prioritizing factors like ease of implementation, control required, and browser compatibility.