/** The following functions are mostly taken from
 *  Headrush AJAX from O'Reilly
 */

function replaceText(el, text) {
  if (el != null) {
    clearText(el);
    var newNode = document.createTextNode(text);
    el.appendChild(newNode);
  }
}

function clearText(el) {
  if (el != null) {
    if (el.childNodes) {
        for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        el.removeChild(childNode);
      }
    }
  }
}

function removeChildNodes(el) {
   while (el.childNodes[0]) {
     el.removeChild(el.childNodes[0]);
   }
}


function getText(el) {
  var text = "";
  if (el != null) {
    if (el.childNodes) {
      for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        if (childNode.nodeValue != null) {
          text = text + childNode.nodeValue;
        }
      }
    }
  }
  return text;
}


/** This javascript function parses window.location
 *  retrieves variables by name that have been provided
 *  by GET on the URI.  Function originally taken from
 *  http://www.activsoftware.com with credit given to
 *  Pete Freitag as author.
 */
function getQueryVariable(variable) {
  var query = window.location.search.substring(1);
  var vars = query.split("&");
  for (var i=0;i<vars.length;i++) {
    var pair = vars[i].split("=");
    if (pair[0] == variable) {
      return pair[1];
    }
  } 
  return null;
}