// this function is needed to work around 
// a bug in IE related to element attributes
function hasClass(obj) {
   var result = false;
   if (obj.getAttributeNode("class") != null) {
       result = obj.getAttributeNode("class").value;
   }
   return result;
}   

function stripe(id) {

  // the flag we'll use to keep track of 
  // whether the current row is odd or even
  var even = false;

  // if arguments are provided to specify the colours
  // of the even & odd rows, then use the them;
  // otherwise use the following defaults:
  var evenColor = arguments[1] ? arguments[1] : "#fff";
  var oddColor = arguments[2] ? arguments[2] : "#eee";

  // obtain a reference to the desired table
  // if no such table exists, abort
  var table = document.getElementById(id);
  if (! table) { return; }
  
  // by definition, tables can have more than one tbody
  // element, so we'll have to get the list of child
  // <tbody>s 
  var tbodies = table.getElementsByTagName("tbody");

  // and iterate through them...
  for (var h = 0; h < tbodies.length; h++) {
  
   // find all the &lt;tr&gt; elements... 
    var trs = tbodies[h].getElementsByTagName("tr");
    
    // ... and iterate through them
    for (var i = 0; i < trs.length; i++) {

      // avoid rows that have a class attribute
      // or backgroundColor style
      if (! hasClass(trs[i]) &&
          ! trs[i].style.backgroundColor) {
    
        // get all the cells in this row...
        var tds = trs[i].getElementsByTagName("td");
      
        // and iterate through them...
        for (var j = 0; j < tds.length; j++) {
      
          var mytd = tds[j];

          // avoid cells that have a class attribute
          // or backgroundColor style
          if (! hasClass(mytd) &&
              ! mytd.style.backgroundColor) {
      
            mytd.style.backgroundColor =
              even ? evenColor : oddColor;
          
          }
        }
      }
      // flip from odd to even, or vice-versa
      even =  ! even;
    }
  }
}