How to add Base64 data to FormData so that it loads as binary

I have base64 data source source code. I am trying to download it as a normal binary download.

From MDN I see that my problem is with Blob , boils down to creating a binary Blob from base64:

var content = 'iVBORw0KGgoAAAANSUhEUgAABUUAAAI/...'; // the image
var blob = new Blob([content], { type: "image/png,base64"});

formData.append("image", blob);

      

        
        
        
      

    

How can I do this safely (= avoid unicode strings)?