Front-end solutions browser downloads the file name problem

// download URL DOC 
the let the href = "Base64 encoding" 
the let fileName = " filename .doc 
// download DOC 
the this . Http. GET (the href, { 
  the observe: ' Response ' , 
  responseType: ' BLOB ' , 
}). Subscribe ( RES: Blob => { 
// return the data stream Blob
   const File = decodeURIComponent (fileName);
   the this ._FileSaverService.save (res.body, File);
   the this .isDownload = to false ; 
}, ERR => {
   the this= .isDownload to false ;
   the this .message.create ( ' error ' , ' download failed! ' ); 
});