title: The file format and extension of 'file.xls' don't match with fileSaver.js
body: <p>I want to save a html table in a excel file, I used fileSaver for angular. But when I download the file and try to open it I receive an annoying popup from excel which say</p>
  
  <p>"The file format and extension of 'report.xls' don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?"</p>
  
  <pre><code>$scope.exportExcel = function(){
  
      var data, table;
      table = document.getElementById('tableReport').innerHTML;
      data = new Blob([table], {
          type: 'application/vnd.ms-excel;charset=charset=utf-8'
      });
      return FileSaver.saveAs(data, 'report.xls');
  };
  </code></pre>
  
  <p>How can I fix this popup? Thanks.</p>