
<!-----------rotate content------------------>
function rotateContent(){
	//hideFeatures();
	if (curindex==(tempindex=Math.floor(Math.random()*(randomcontent.length)))){
		curindex=curindex==0? 1 : curindex-1
	}
	else
		curindex=tempindex;
	//document.randomSelect.value=randomcontent[curindex];
	
	//document.getElementById('randomSelect').style.border='2px solid #c00';
	
	//document.getElementById('randomSelect').innerHTML=randomcontent[curindex];
}
<!-----------get elements by class name------------------>
document.getElementsByClassName = function(clsName){
    var retVal = new Array();
    var elements = document.getElementsByTagName("*");
    for(var i = 0;i < elements.length;i++){
        if(elements[i].className.indexOf(" ") >= 0){
            var classes = elements[i].className.split(" ");
            for(var j = 0;j < classes.length;j++){
                if(classes[j] == clsName)
                    retVal.push(elements[i]);
            }
        }
        else if(elements[i].className == clsName)
            retVal.push(elements[i]);
    }
    return retVal;
}
<!----------hide features ------------------->
function randomizeContentList(/*...*/){

         for(var i=0;i<arguments.length;i++) {
           //alert('randomize:' + arguments[i]);
         randomizeContent(arguments[i]);
         }
}

function randomizeContent(section2hide){
 var contents = document.getElementsByClassName(section2hide);
 var contentsLength=contents.length;

 // alert('hiding: ' + contentsLength);

	// contents = document.getElementsByClassName('hideShow');
	 for(var i = 0; i < contents.length; i++) {
		contents[i].style.display = 'none';
	  }
	  showFeature(section2hide);
  }
  function showFeature(section2hide){
  var contents = document.getElementsByClassName(section2hide);
  var contentsLength=contents.length;
  var tempindex=Math.floor(Math.random()*(contents.length));
//alert( 'show: '+tempindex);
		contents = document.getElementsByClassName(section2hide);
	//alert(contents[tempindex].style.display);
	
		//contents[tempindex].style.display= '';
		contents[tempindex].style.display= 'block';
		
	  
  }