getElementByTagName not working?

Question

In the code below, I am applying a different background color to all even rows by dynamically assigning the class \"even\" to them using javascript. I am calling the alternamte(

Answer 1

Use getElementsByTagName instead of getElementByTagName (getElementsByTagName return multiple node elements )

 var table = document.getElementsByTagName("table")[0], trs, rl;  
 vat tl= table.length;
 while(tl--){
        trs = tables[tl].getElementsByTagName("tr");
        rl = trs.length;
        while(rl--){
           if(rl % 2 == 0){ 
              trs[rl].className = "even"; 
           } 
        }
  }