How To Build Pdf File From Binary String Returned From A Web Service Using Javascript

Have you ever needed to generate a PDF file from a binary string received from a web service using JavaScript? It might sound tricky at first, but fear not! In this article, we'll guide you through the steps on how to accomplish this task seamlessly.

To start off, let's first understand the basics. When a web service returns a binary string, it means that the data is represented in a binary format rather than plain text or other formats. This binary string could contain various types of data, such as images, documents, or in our case, a PDF file.

The key to building a PDF file from a binary string in JavaScript lies in leveraging the power of the HTML5 Blob API. A Blob (Binary Large Object) represents raw data, allowing you to work with binary data directly. By utilizing Blobs, we can convert the binary string into a Blob object and further use it to create a downloadable PDF file.

Now, let's dive into the step-by-step process:

1. Receive the Binary String: When you make a request to the web service and receive the binary string in response, store it in a variable for further processing.

2. Convert Binary String to Blob: To convert the binary string into a Blob object, you can use the following code snippet:

function binaryStringToBlob(binaryString) {
  const byteCharacters = atob(binaryString);
  const byteNumbers = new Array(byteCharacters.length);
  for (let i = 0; i < byteCharacters.length; i++) {
    byteNumbers[i] = byteCharacters.charCodeAt(i);
  }
  const byteArray = new Uint8Array(byteNumbers);
  return new Blob([byteArray], { type: 'application/pdf' });
}

In the `binaryStringToBlob` function, we first decode the binary string using `atob`, then convert it into an array of byte values. Finally, we create a Blob object with the byte array and specify the MIME type as 'application/pdf'.

3. Create a Downloadable PDF File: After converting the binary string to a Blob, you can create a download link for the PDF file using the following JavaScript code:

function downloadPDFFromBlob(blob, fileName) {
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = fileName;
  document.body.appendChild(a);
  a.click();
  window.URL.revokeObjectURL(url);
}

In the `downloadPDFFromBlob` function, we create a URL for the Blob object, create a new anchor element ``, set the download attribute to specify the file name, trigger a click event to initiate the download, and finally revoke the URL to clean up.