scroller.html

<div class="phrases">
  <div class="phrase">First</div>
  <div class="phrase">Second</div>
  <div class="phrase">Third</div>
  <div class="phrase">Fourth</div>
</div>

<script>
;(function(){

var timeout = 1000,
    index = 0,
    phrases = Array.prototype.slice.call(
      document.querySelectorAll('.phrase')
    )

phrases.forEach(function(ele){
  ele.style.display = 'none'
})

window.setInterval(function(){
  phrases.forEach(function(ele){
    ele.style.display = 'none'
  })
  
  phrases[index].style.display = 'block'
  index++
  if (index === phrases.length) index = 0
}, timeout)

})();
</script>