Change the Slug of a Blob PDF Opened in a New Tab Using jQuery

Handling Blob PDF Slugs in New Tabs with JavaScript

Generating PDFs from a webpage is a common requirement in web development. You might need to create a dynamic PDF, open it in a new tab, and provide a custom filename or slug for the file. However, working with JavaScript blobs presents a challenge when it comes to changing the slug of the file.

While blobs are essential for handling downloadable content, one limitation is the inability to directly set or change the filename property. Developers often try to assign names or filenames to blobs when generating files, but such attempts usually fail due to browser restrictions.

If you've tried setting properties like blob.name or blob.filename in your code without success, you're not alone. This is a common issue faced when trying to customize blob behavior. The need to open the generated PDF with a custom slug can make this more frustrating.

In this article, we’ll explore potential solutions and workarounds for generating PDFs using blobs in JavaScript and ensuring the file opens in a new tab with the correct custom slug. We'll also look at practical code examples to guide you through this process.

Generating PDF with Custom Slug Using JavaScript and jQuery

The scripts provided focus on addressing the challenge of opening a PDF file generated from a webpage in a new tab with a custom filename or slug. One of the main issues developers encounter when working with blobs in JavaScript is the inability to directly assign a filename, which is essential for setting a custom slug. In our solution, the key technique involves creating a Blob from the PDF content, which we generate dynamically. Using the URL.createObjectURL() function, we convert this Blob into a resource that the browser can open or download.

Once the Blob URL is created, we use window.open() to display the PDF in a new tab, which is often required in situations where a user needs to preview or print the document. Since the blob itself doesn’t support naming the file, we bypass this limitation by creating a hidden link element and assigning the desired filename using the download attribute. This hidden link is then programmatically "clicked" to trigger the download with the correct filename. This combination of methods is a common workaround for the blob naming limitation in JavaScript.

For server-side solutions, we use Node.js and Express to serve PDF files with a custom filename directly. By utilizing fs.createReadStream(), the file is streamed to the client efficiently, allowing the server to handle large files without loading them into memory all at once. The res.setHeader() command is crucial here, as it ensures that the HTTP response headers specify the custom filename and MIME type (application/pdf). This method is ideal for more complex applications where the PDF is generated or stored on the server.

These scripts are designed to be modular and reusable. Whether you're working in a client-side environment using JavaScript or a backend solution with Node.js, these techniques ensure that your PDFs are delivered or opened with the correct filename. Both approaches are optimized for performance and can handle scenarios where PDFs are generated dynamically or stored server-side. By providing both front-end and back-end solutions, this ensures flexibility, allowing you to implement the most appropriate method depending on your project’s needs.

// Function to generate and open PDF in a new tab with custom filename
function openPDFWithCustomName(data, filename) {
  // Create a Blob object from the data (PDF content)
  var blob = new Blob([data], { type: 'application/pdf' });
  // Create a URL for the Blob object
  var blobURL = window.URL.createObjectURL(blob);
  // Create a temporary link to trigger the download
  var link = document.createElement('a');
  link.href = blobURL;
  link.download = filename; // Custom slug or filename
  // Open in a new tab
  window.open(blobURL, '_blank');
}

// Example usage: data could be the generated PDF content
var pdfData = '...'; // Your PDF binary data here
openPDFWithCustomName(pdfData, 'custom-slug.pdf');

// Require necessary modules
const express = require('express');
const fs = require('fs');
const path = require('path');
const app = express();

// Serve generated PDF with custom slug
app.get('/generate-pdf', (req, res) => {
  const pdfFilePath = path.join(__dirname, 'test.pdf');
  res.setHeader('Content-Disposition', 'attachment; filename="custom-slug.pdf"');
  res.setHeader('Content-Type', 'application/pdf');
  const pdfStream = fs.createReadStream(pdfFilePath);
  pdfStream.pipe(res);
});

// Start the server
app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

// To test, navigate to http://localhost:3000/generate-pdf

// Function to open PDF in new tab with custom filename using download attribute
function openPDFInNewTab(data, filename) {
  var blob = new Blob([data], { type: 'application/pdf' });
  var url = window.URL.createObjectURL(blob);
  var link = document.createElement('a');
  link.href = url;
  link.download = filename;
  link.click(); // Triggers the download
  window.open(url, '_blank'); // Opens PDF in a new tab
}

// Example call
var pdfData = '...'; // PDF binary content
openPDFInNewTab(pdfData, 'new-slug.pdf');

Understanding the Limits and Solutions for Blob Filenames in JavaScript

One of the main challenges when working with Blob objects in JavaScript is the limitation around setting filenames. When generating a PDF or any file type, blobs do not inherently support a direct method for assigning a custom filename. This becomes particularly problematic when trying to open these files in a new tab or trigger a download with a specific slug. The browser’s default behavior is to generate an arbitrary name, which is not always user-friendly or appropriate for the context of the file.

To overcome this limitation, developers can use the HTML5 download attribute, which allows for defining a filename for the file being downloaded. By creating an anchor element dynamically in JavaScript and setting the download attribute to the desired filename, we can control the file name when the blob content is downloaded. However, this method doesn’t impact the name when the blob is opened in a new tab, as this is controlled by the browser’s built-in functionality for rendering blob URLs.

Another approach is to serve the file from the backend using a framework like Node.js or Express, where custom headers can be set to control the filename of the file sent to the client. The Content-Disposition header allows you to specify the name of the file regardless of whether it is being downloaded or opened in a new tab. This method is more flexible for server-side rendered content, but for client-side JavaScript blobs, the download attribute is the most effective solution.