code: function getFilename( file, postfix ) {
      let filenameParts;
      if ( typeof file === 'object' && file !== null && file.name ) {
          postfix = postfix || '';
          filenameParts = file.name.split( '.' );
          if ( filenameParts.length > 1 ) {
              filenameParts[ filenameParts.length - 2 ] += postfix;
          } else if ( filenameParts.length === 1 ) {
              filenameParts[ 0 ] += postfix;
          }
          return filenameParts.join( '.' );
      }
      return '';
  }
docs: Because iOS gives any camera-provided file the same filename, we need to a unique-ified filename.  See https://github.com/kobotoolbox/enketo-express/issues/374