code: function b64toBlob(b64Data, contentType, sliceSize) {
  	contentType = contentType || '';
  	sliceSize = sliceSize || 512;
  
  	var byteCharacters = atob(b64Data);
  	var byteArrays = [];
  
  	for (var offset = 0; offset < byteCharacters.length; offset += sliceSize) {
  		var slice = byteCharacters.slice(offset, offset + sliceSize);
  
  		var byteNumbers = new Array(slice.length);
  		for (var i = 0; i < slice.length; i++) {
  			byteNumbers[i] = slice.charCodeAt(i);
  		}
  
  		var byteArray = new Uint8Array(byteNumbers);
  
  		byteArrays.push(byteArray);
  	}
  
  	var blob = new Blob(byteArrays, {type: contentType});
  	return blob;
  }
docs: From https://github.com/jeremybanks/b64-to-blob