

function setAlternaterRows(id){	 
	 if(document.getElementsByTagName){  
	   var table = document.getElementById(id);  
	   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";
	     }      
	   }
	 }
	}

call the function as setAlternaterRows('youtableid')