function alternate()
{
	if(document.getElementsByTagName)
	{  
		var tables = document.getElementsByTagName("table");
		for(j=0; j < tables.length; j++)
		{
			table = tables[j];
			var rows = table.getElementsByTagName("tr");  
			for(i = 0; i < rows.length; i++)
			{
				//manipulate rows
				if(i % 2 == 0)
				{
					rows[i].className = "even";
				}
				else
				{
					rows[i].className = "odd";
				}      
			}
		}
	}
}