code: function getPrintStyleSheet() {
      let sheet;
      // document.styleSheets is an Object not an Array!
      for ( const i in document.styleSheets ) {
          if ( document.styleSheets.hasOwnProperty( i ) ) {
              sheet = document.styleSheets[ i ];
              if ( sheet.media.mediaText === 'print' ) {
                  return sheet;
              }
          }
      }
      return null;
  }
docs: Gets print stylesheets
  @return {Element} [description]