code: function dataURLToBlob(dataURL) {
    // Code taken from https://github.com/ebidel/filer.js
    var parts = dataURL.split(';base64,');
    var contentType = parts[0].split(":")[1];
    var raw = window.atob(parts[1]);
    var rawLength = raw.length;
    var uInt8Array = new Uint8Array(rawLength);
  
    for (var i = 0; i < rawLength; ++i) {
      uInt8Array[i] = raw.charCodeAt(i);
    }
  
    return new Blob([uInt8Array], { type: contentType });
  }
docs: One could simply use Canvas#toBlob method instead, but it's just to show that it can be done using result of SignaturePad#toDataURL.