Create PDFs with NodeJS and Puppeteer

Create PDFs with NodeJS and Puppeteer

Table of Contents

1. Introduction
2. Overview of Puppeteer and PDF Generation
3. Setting up Puppeteer and Required Dependencies
4. Launching a New Browser with Puppeteer
5. Configuring the Page for PDF Generation
6. Rendering HTML Content to PDF
7. Customizing PDF Options
8. Compiling Handlebars Templates
9. Reading Data from the File System
10. Including Helpers and Custom Functions
11. Generating PDF from Handlebars Templates
12. Creating a More Complex Example
13. Conclusion

Introduction

In this article, we will explore the capabilities of Puppeteer for PDF generation. Puppeteer is a powerful tool that allows us to control and automate headless Chrome or Chromium. We will specifically focus on creating PDFs using Handlebars templates and manipulating them using Puppeteer.

Overview of Puppeteer and PDF Generation

Puppeteer is a Node.js library that provides a high-level API for controlling a headless Chrome or Chromium browser. It allows us to perform various tasks such as generating screenshots, scraping web pages, and interacting with user interfaces. PDF generation is one of the many great uses of Puppeteer, enabling us to convert HTML content into PDFs with ease.

Setting up Puppeteer and Required Dependencies

To get started with Puppeteer, we need to install the necessary dependencies. We can do this by running the following commands:

npm install puppeteer
npm install fs-extra

Puppeteer is required to control the browser, while fs-extra allows us to interact with the file system asynchronously, which is beneficial for handling templates and data.

Launching a New Browser with Puppeteer

To generate a PDF, we first need to launch a new instance of the browser using Puppeteer. We can achieve this by adding the following code:

const puppeteer = require('puppeteer');

async function generatePDF() {
  try {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();
    // Additional code here
  } catch (error) {
    console.log('An error occurred:', error);
  }
}

generatePDF();

By invoking the launch() function, Puppeteer will create a new instance of the browser, and the newPage() function will create a new tab within the browser.

Configuring the Page for PDF Generation

Before rendering HTML content to PDF, we need to configure the page to emulate a screen media type. This ensures that the page does not try to emulate print stylesheets or other media types. We can accomplish this by adding the following code:

await page.emulateMediaType('screen');

Additionally, to enable background colors in the PDF, we can include the following option when calling the page.pdf() function:

await page.pdf({
  path: 'myPDF.pdf',
  format: 'A4',
  printBackground: true
});

Rendering HTML Content to PDF

To generate a PDF from HTML content, we can use the page.setContent() function to set the content of the page. Here's an example:

await page.setContent('<h1>Hello</h1>');

Once the HTML content is set, we can call the page.pdf() function to generate the PDF. It accepts an options object that allows us to specify the path, format, and other settings for the output file.

Customizing PDF Options

When generating a PDF using Puppeteer, we have the flexibility to customize various options. For example, we can specify the file path where the PDF will be saved, the paper format (such as A4 or Letter), and whether to include the background color. Puppeteer provides a comprehensive list of options that can be customized based on specific requirements.

Compiling Handlebars Templates

Handlebars is a popular templating language that allows us to dynamically generate HTML content. To render a Handlebars template, we need to compile it using the handlebars.compile() function. Here's an example:

const handlebars = require('handlebars');

function compileTemplate(templateName, data) {
  const template = fs.readFileSync(`templates/${templateName}.hbs`, 'utf-8');
  const compiledTemplate = handlebars.compile(template);
  const html = compiledTemplate(data);
  return html;
}

In this code snippet, we read the template file from the file system and compile it using Handlebars. The resulting compiled template is then populated with the provided data to generate the final HTML content.

Reading Data from the File System

To fetch data for our template, we can read it from the file system. This can be achieved using the fs-extra module, which provides additional functionality on top of the built-in fs module. We can use the fs.readFileSync() function to retrieve data from a JSON file. Here's an example:

const fs = require('fs-extra');

const data = fs.readFileSync('data.json', 'utf-8');
const jsonData = JSON.parse(data);

By reading the file as UTF-8 and parsing it as JSON, we can access the data as a JavaScript object.

Including Helpers and Custom Functions

Handlebars allows the inclusion of custom helpers and functions to extend its functionality. In our case, we have a helper to format dates using the Moment.js library. To utilize this helper, we need to register it with Handlebars. For example:

const moment = require('moment');

handlebars.registerHelper('formatDate', function(date) {
  return moment(date).format('MMMM Do YYYY');
});

With this helper registered, we can use it within our Handlebars templates.

Generating PDF from Handlebars Templates

To generate a PDF using a Handlebars template, we first need to compile the template and populate it with the necessary data. We can then set the rendered HTML as the content of the page and call the page.pdf() function to generate the PDF. Here's an example:

const html = compileTemplate('shotList', data);
await page.setContent(html);
await page.pdf({ path: 'myPDF.pdf', format: 'A4', printBackground: true });

This code snippet demonstrates how to render a Handlebars template, set it as the content of the page, and generate the resulting PDF.

Creating a More Complex Example

In a more complex scenario, we can combine the concepts discussed so far to generate a PDF that includes dynamic data from a database. By integrating Puppeteer with Handlebars, we can create a powerful PDF generation system. This allows us to design custom templates, retrieve data from a database, and produce professional PDF documents.

Conclusion

In this article, we explored the process of generating PDFs using Puppeteer and Handlebars templates. We learned how to set up Puppeteer, configure the page, render HTML content, and customize PDF options. Additionally, we discovered how to compile Handlebars templates, read data from the file system, and include custom helpers and functions. By combining these techniques, we can create dynamic and visually appealing PDF documents. Puppeteer's capabilities enable us to automate the generation of PDFs for various purposes. Whether it's generating reports, invoices, or any other type of printable document, Puppeteer provides a reliable and flexible solution.

FAQ

Q: Can Puppeteer generate PDFs from any HTML content? A: Yes, Puppeteer can generate PDFs from any HTML content. It allows you to modify the HTML as needed before generating the PDF.

Q: Can I use Puppeteer to generate PDFs from multiple pages? A: Yes, Puppeteer has the ability to generate PDFs from multiple pages. You can navigate between pages and capture their contents individually.

Q: Is it possible to include images or external resources in the PDF generated by Puppeteer? A: Yes, Puppeteer can include images and external resources in the PDF. By properly referencing the URLs or local file paths, Puppeteer will fetch and embed those resources in the PDF.

Q: Can I specify the page size and orientation when generating a PDF with Puppeteer? A: Yes, Puppeteer allows you to specify the page size and orientation when generating a PDF. You can choose from a variety of standard formats, such as A4 or Letter, and set the orientation to portrait or landscape.

Q: Is there a limit to the number of PDFs Puppeteer can generate? A: There is no inherent limit to the number of PDFs Puppeteer can generate. However, it is recommended to manage resources effectively and avoid memory leaks when generating a large number of PDFs.

Q: Can I password-protect the PDFs generated by Puppeteer? A: No, Puppeteer does not provide built-in functionality for password protection of PDFs. However, you can use third-party libraries or tools to add password protection to the generated PDFs.

Q: How can I handle errors or exceptions while generating PDFs with Puppeteer? A: You can use try-catch blocks to handle errors or exceptions that may occur during the PDF generation process. By wrapping the relevant code in a try-catch block, you can gracefully handle any errors and log or display appropriate messages to the user.

Q: Is Puppeteer suitable for generating highly customized and visually complex PDFs? A: Yes, Puppeteer is highly suitable for generating highly customized and visually complex PDFs. With the flexibility of Handlebars templates and the ability to manipulate HTML content, you can create intricate PDF layouts and designs.

Q: Are there any alternatives to Puppeteer for generating PDFs? A: Yes, there are alternatives to Puppeteer for generating PDFs. Some popular alternatives include wkhtmltopdf, PDFKit, and PrinceXML. Each tool has its own features, advantages, and use cases, so it's worth exploring different options based on your specific requirements.