/*
 * Adds previous and next buttons to rotate the "Did You Know?" images.
*/

(function(){

var old_onload = window.onload ? window.onload : function(){};

window.onload = function(){

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  var dyk_images = [
   {alt : "Zero the number of new TB drugs", src : "/page/-/images/DYK/18.jpg"},{alt : "The standard diagnostic test", src : "/page/-/images/DYK/16.jpg"},{alt : "TB has been around for at least 4000 years", src : "/page/-/images/DYK/15.jpg"},{alt : "There is no effective vaccine for TB", src : "/page/-/images/DYK/17.jpg"},{alt : "Someone with untreated active TB", src : "/page/-/images/DYK/14.jpg"},{alt : "The World Health Organization has declared TB", src : "/page/-/images/DYK/12.jpg"},{alt : "Coughing Sneezing Laughing Singing", src : "/page/-/images/DYK/13.jpg"},{alt : "TB treatment is one of the most cost-effective", src : "/page/-/images/DYK/9.jpg"},{alt : "A full course of treatment", src : "/page/-/images/DYK/10.jpg"},{alt : "The world spends $35 billion annually", src : "/page/-/images/DYK/11.jpg"},{alt : "TB is the world’s leading infectious killer", src : "/page/-/images/DYK/8.jpg"},{alt : "1 in 3 people are infected", src : "/page/-/images/DYK/7.jpg"},{alt : "Without proper treatment", src : "/page/-/images/DYK/6.jpg"},{alt : "TB claims more lives than any other curable infectious disease", src : "/page/-/images/DYK/5.jpg"},{alt : "1.7 Million People Die from TB Each Year", src : "/page/-/images/DYK/4.jpg"},{alt : "Over 9 million people become sick with TB each year.", src : "/page/-/images/DYK/3.jpg"},{alt : "TB is the leading killer of people with HIV/AIDS.", src : "/page/-/images/DYK/2.jpg"},{alt : "TB kills one person every 20 seconds.", src : "/page/-/images/DYK/1.jpg"}
  ];

  var previous = document.createElement("a");
  var next = document.createElement("a");

  previous.href = '#';
  next.href = '#';

  previous.appendChild(document.createTextNode('Previous'));
  next.appendChild(document.createTextNode('Next'));

  previous.className = 'previous';
  next.className = 'next';

  previous.onclick = function(e) {
    var evt = e ? e : event;
    var current_image = document.getElementById('dyk');

    for (var i=0; i < dyk_images.length; i++) {
      if (current_image.src.indexOf(dyk_images[i].src) >= 0) {
        current_image.src = (i == 0) ? dyk_images[dyk_images.length - 1].src : dyk_images[i - 1].src;
        current_image.alt = (i == 0) ? dyk_images[dyk_images.length - 1].alt : dyk_images[i - 1].alt;
        break;
      }
    }

    if (evt.preventDefault) {evt.preventDefault();} else {
      evt.returnValue = false;
    }
  };

  next.onclick = function(e) {
    var evt = e ? e : event; 
    var current_image = document.getElementById('dyk');

    for (var i=0; i < dyk_images.length; i++) {
      if (current_image.src.indexOf(dyk_images[i].src) >= 0) {
        current_image.src = (i == dyk_images.length - 1) ? dyk_images[0].src : dyk_images[i + 1].src;
        current_image.alt = (i == dyk_images.length - 1) ? dyk_images[0].alt : dyk_images[i + 1].alt;
        break;
      }
    }

    if (evt.preventDefault) {evt.preventDefault();} else {
      evt.returnValue = false;
    }
  };

  var dyk = document.getElementById('dyk');

  dyk.parentNode.appendChild(previous);
  dyk.parentNode.appendChild(next);

};

})();