function init(){

  var inactiveTabs = getElementsByClass('tab');

  var active=document.getElementById('home');  

  

  showLoading();

  request('home');

  

  active.onclick = function(){    

    setActive('home');

    showLoading();

    request(this.id);

  }



  for(i = 0; i < inactiveTabs.length; i++){

    inactiveTabs[i].onclick = function(){      

      setActive(this.id);

      showLoading();

      request(this.id);

      //@param request(what,where)

    }

  }

}

function getElementsByClass(searchClass, node, tag){

  var classElements = new Array();



  if(node == null){

    node = document;

  }



  if(tag == null){

    tag = '*';

  }



  var els = node.getElementsByTagName(tag);

  var elsLen = els.length;

  var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");



  for(i = 0, j = 0; i < elsLen; i++){

    if(pattern.test(els[i].className)){

      classElements[j] = els[i];

      j++;

    }

  }



  return classElements;

}

function request(what){

  var ajaxRequest;

  var target = document.getElementById('contents');

  try{

    ajaxRequest = new XMLHttpRequest();

  }

  catch(e){

    try{

      ajaxRequest = new ActiveXObject('Msxml2.XMLHTTP');

    }

    catch(e){

      try{

        ajaxRequest = new ActiveXObject('Microsoft.XMLHTTP');

      }

      catch(e){

        alert('Your browser does not support AJAX!');

        return false;

      }

    }

  }

  antiCache = new Date().getTime();

  ajaxRequest.open('GET', what + '.html', true);

  ajaxRequest.send(null);

  

  ajaxRequest.onreadystatechange = function(){

    if(ajaxRequest.readyState == 4){

      target.innerHTML = ajaxRequest.responseText;

    }

  }

}

function showLoading(){

  var target = document.getElementById('contents');

  target.innerHTML = '<p class="head"><img src="images/ajax-loader.gif" alt="Loading Image" /> Loading...</p>';

}

function setActive(clickedTab){

  var clickedTab = document.getElementById(clickedTab);

  var activeTab = getElementsByClass('active')[0];



  activeTab.className = 'tab';

  clickedTab.className = 'active';

}