function doHighlight(bodyText, searchTerm, highlightStartTag, highlightEndTag)
{
  // find all occurences of the search term in the given text,
  // and add some "highlight" tags to them (we're not using a
  // regular expression search, because we want to filter out
  // matches that occur within HTML tags and script blocks, so
  // we have to do a little extra validation)
  var newText = "";
  var i = 0, j = 0;
  var lcSearchTerm = searchTerm.toLowerCase();
  var lcBodyText = bodyText.toLowerCase();

  while ((i = lcBodyText.indexOf(lcSearchTerm, i)) > 0) {
    if (lcBodyText.lastIndexOf(">", i) >= lcBodyText.lastIndexOf("<", i)) {
      if (lcBodyText.lastIndexOf("/script>", i) >= lcBodyText.lastIndexOf("<script", i)) {
        newText += bodyText.substring(j, i) + highlightStartTag + bodyText.substr(i, searchTerm.length) + highlightEndTag;
        i += searchTerm.length;
        j = i;
        continue;
      }
    }
    i++;
  }
  newText += bodyText.substring(j, bodyText.length);

  return newText;
}

function highlightSearchTerms(searchText)
{
  if (!document.body || typeof(document.body.innerHTML) == "undefined")
    return false;

  var bodyText = document.body.innerHTML;
  searchArray = searchText.split(" ");

  for (var i = 0; i < searchArray.length; i++)
    bodyText = doHighlight(bodyText, searchArray[i], '<span class="highlight">', '</span>');

  document.body.innerHTML = bodyText;
  return true;
}