API returns a PDF file (byteArray) and it needs to be downloaded using Javascript

When I execute API in SwaggerUI it returns OK and I get download link and it works.

It’s used for PDF files, this is the kind of data

And I need to download this using javascript, I tried converting it to base64 first and then downloading, but I’d never even get it to log in the console

For example

const binaryData = new Uint8Array([data.action_api_response]);
const base64Data = btoa(String.fromCharCode.apply(null, binaryData));

function arrayBufferToBase64(buffer) {
   let binary = '';
   const bytes = new Uint8Array(buffer);
   const chunkSize = 1024;
   
   for (let i = 0; i < bytes.length; i += chunkSize) {
       const chunk = bytes.slice(i, i + chunkSize);
       binary += String.fromCharCode.apply(null, chunk);
   }
   
   console.log(btoa(binary));
}

arrayBufferToBase64(buffer);

This returns an empty string.

I wanted to convert it to base64 first cause I already have a function that works with base64, but I’ve never done downloading byte array streams so not sure how to solve this.

Thanks in advance