var praestaPos = 140;

function scroll() {
  praestaPos = scrollTicker( "praestaTicker", praestaPos );
}

function scrollTicker( id, pos ) {

  var div = document.getElementById(id);

  if (pos < (div.offsetWidth * -1)) {
    pos = 340;
  } else {
    pos -= 1;
  }

  div.style.left = pos + "px";
 
  return pos;

}

window.setInterval( 'scroll()', 35 );