function hasClass(obj)
{
	var res = false;
	if(obj.getAttributeNode("class") != null)
	{
		res = obj.getAttributeNode("class").value;
	}
	return res;
}

function zebrer(id)
{
	var bool = false;

	var color1 = "#222";
	var color2 = "#000";
  
	var table = document.getElementById(id);
    
	var trs = table.getElementsByTagName("tr");

	for(var i=0 ; i<trs.length ; i++)
	{
		if(!hasClass(trs[i]))
		{
			var tds = trs[i].getElementsByTagName("td");
        
			for(var j=0 ; j<tds.length ; j++)
			{
				var currenttd = tds[j];
			
				if(bool)
					currenttd.style.backgroundColor = color1;
				else
					currenttd.style.backgroundColor = color2;
			}
			bool =  !bool;
		}
	}
}