function $() 
{ 
  var elements = new Array(); 
  for (var i = 0; i < arguments.length; i++) 
  { 
    var element = arguments[i]; 
    if (typeof element == 'string') 
      element = document.getElementById(element); 
    if (arguments.length == 1) 
      return element; 
    elements.push(element); 
  } 
  return elements; 
}
<!-------------------------------->
function ct(id) {
	for (var i = 1; i < 4; i++) {
		if (i == id) {
			$("ct"+i).className = "cta";
			$("divct"+i).style.display = "block";
		} else {
			$("ct"+i).className = "ctb";
			$("divct"+i).style.display = "none";
		}
	}
}