Very Simple, Very Smooth, JavaScript Marquee

(function($) {
  $.fn.textWidth = function() {
    var calc="<span style="display:none">" + $(this).text() + '</span>';
    $('body').append(calc);
    var width = $('body').find('span:last').width();
    $('body').find('span:last').remove();
    return width;
  };

  $.fn.marquee = function(args) {
    var that = $(this);
    var textWidth = that.textWidth(),
      offset = that.width(),
      width = offset,
      css = {
        'text-indent': that.css('text-indent'),
        'overflow': that.css('overflow'),
        'white-space': that.css('white-space')
      },
      marqueeCss = {
        'text-indent': width,
        'overflow': 'hidden',
        'white-space': 'nowrap'
      },
      args = $.extend(true, {
        count: -1,
        speed: 1e1,
        leftToRight: false
      }, args),
      i = 0,
      stop = textWidth * -1,
      dfd = $.Deferred();

    function go() {
      if (!that.length) return dfd.reject();
      if (width == stop) {
        i++;
        if (i == args.count) {
          that.css(css);
          return dfd.resolve();
        }
        if (args.leftToRight) {
          width = textWidth * -1;
        } else {
          width = offset;
        }
      }
      that.css('text-indent', width + 'px');
      if (args.leftToRight) {
        width++;
      } else {
        width--;
      }
      setTimeout(go, args.speed);
    };
    if (args.leftToRight) {
      width = textWidth * -1;
      width++;
      stop = offset;
    } else {
      width--;
    }
    that.css(marqueeCss);
    go();
    return dfd.promise();
  };
})(jQuery);

$('h1').marquee();
$('h2').marquee({
  count: 2
});
$('h3').marquee({
  speed: 5
});
$('h4').marquee({
  leftToRight: true
});
$('h5').marquee({
  count: 1,
  speed: 2
}).done(function() {
  $('h5').css('color', '#f00');
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<h1>Hello World!</h1>
<h2>I'll marquee twice</h2>
<h3>I go fast!</h3>
<h4>Left to right</h4>
<h5>I'll defer that question</h5>