In filePath I get a .csv file with an but e.target.result return me a .xls file.

can I change the file extension ? or

can I maintain the original extension?

thanks!!

let reader = new FileReader();

reader.onload = ( (theFile) =>{
  return (e) => {

    // e.target.result ;
    resolve( e.target.result );
  };
})( filePath );

// Read in the file as a data URL.
reader.readAsDataURL( filePath );