title: Why FileReader of Javascript it does not maintain the .csv extension
body: <p>In filePath I get a .csv file with an  but e.target.result return me a .xls file.</p>
  <p>can I change the file extension ? or</p>
  <p>can I maintain the original extension?</p>
  <p>thanks!!</p>
  <pre><code>let reader = new FileReader();
  
  reader.onload = ( (theFile) =&gt;{
    return (e) =&gt; {
  
      // e.target.result ;
      resolve( e.target.result );
    };
  })( filePath );
  
  // Read in the file as a data URL.
  reader.readAsDataURL( filePath );
  </code></pre>