getElementsByClass

function getElementsByClass(searchClass,node,tag) {
  var classElements = new Array();
  if (node == null)
    node = document;
  if (tag == null)
    tag = '*';
  var els = node.getElementsByTagName (tag);
  var elsLen = els.length;
  var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
  for (i = 0, j = 0; i < elsLen; i++) {
    if (pattern.test(els[i].className) ) {
      classElements[j] = els[i];
      classElements[j].style.display="none";
      //alert(classElements[j]);
      j++;
    }
  }
  return classElements;
  //alert(classElements);
}

u  can use this like
getElementsByClass("oddp2",null,"p")