c# base64 to js Blob convertion

b64toBlob.js

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;
  }