//constants
var BASE_URL = '/';

// get element by ID
function _id(id){
	return document.getElementById(id);
}

//get a suitable ajax handler
function getAjax(){
	if (window.XMLHttpRequest){
		return new XMLHttpRequest();
	}
	else if (window.ActiveXObject){
		return new ActiveXObject("Microsoft.XMLHTTP");
	}
	else{
		return false;
	}
}

function isInteger (s)
   {
      var i;

      if (isEmpty(s))
      if (isInteger.arguments.length == 1) return 0;
      else return (isInteger.arguments[1] == true);

      for (i = 0; i < s.length; i++)
      {
         var c = s.charAt(i);

         if (!isDigit(c)) return false;
      }

      return true;
   }

   function isEmpty(s)
   {
      return ((s == null) || (s.length == 0))
   }

   function isDigit (c)
   {
      return ((c >= "0") && (c <= "9"))
   }