function quoteChanger() {

  // get quotes

  var quotes = [];
  var divTag = document.getElementById('quote-changer');
  var pTags = divTag.getElementsByTagName('p');

  for (var i=0; i < pTags.length; i++) {
    quotes[i] = pTags[i];
    quotes[i].style.display = 'none';
  }


  // display current quote at intervals

  var counter = 0;
  var currentQuote = quotes[counter];
  var duration = 15000;

  currentQuote.style.display = 'block';

  setTimeout(function(){displayQuote();}, duration);


  function displayQuote() {
    currentQuote = quotes[counter];
    currentQuote.style.display = 'none';
    if (counter == quotes.length - 1) {
      counter = 0;
      currentQuote = quotes[counter];
      currentQuote.style.display = 'block';
      setTimeout(function(){displayQuote();}, duration);
     } else {
      counter = counter + 1;
      currentQuote = quotes[counter];
      currentQuote.style.display = 'block';
      setTimeout(function(){displayQuote();}, duration);
    }
  }

}

// run function when window loads

addEvent(window, 'load', quoteChanger, false);

function addEvent(elm, evType, fn, useCapture) {
  if (elm.addEventListener) {
    elm.addEventListener(evType, fn, useCapture);
    return true;
  } else if (elm.attachEvent) {
    var r = elm.attachEvent('on' + evType, fn);
    return r;
  } else {
    elm['on' + evType] = fn;
  }
}