var interval = 30; 
var items = 5;
var current = Math.floor(Math.random()*items);

function rotater() {
  if (current<items){
    document.getElementById("testimonials").innerHTML = document.getElementById(current+1).innerHTML;
    current++;
  }
  else{
    current=0;
    document.getElementById("testimonials").innerHTML = document.getElementById(current+1).innerHTML;
  }
  setTimeout("rotater()",interval*1000); // rotater() executes after delay milliseconds
}


window.onload=rotater;