Show HN: JavaScript snippet to highlight new posts

Hi all. I wanted an easy way to highlight new posts, without basing it on the last time I visited a page. The snippet is as follows, if any of you folks would like to use it:

  /**
   * Usage: highlight('newpost', 3, 'hours');
   *
   * This will add the class 'newpost' to any post made within
   * the past 3 hours. This includes, for example:
   *
   * 3 hours ago
   * 45 minutes ago
   * 22 seconds ago
   */
  function highlight(className, number, type) {
    var types = ['second', 'seconds',
                 'minute', 'minutes',
                 'hour', 'hours',
                 'day', 'days'];

    // Types are inclusive, so if we filtered to 'minutes', then
    // we always want posts that were made 'seconds' ago.
    types = types.slice(0, types.indexOf(type) + 1);

    // Any link with 'item?id' is assumed to be a timestamp.
    var posts = document.querySelectorAll('a[href*="item?id"]');

    // Loop through the number of posts, since we need to access
    // each post using NodeList#item.
    for(var i = 0; i < posts.length; i++) {
      var post = posts.item(i);

      try {
        // The leftmost integer.
        var label_number = parseInt(post.innerHTML.match(/^\d+/));

        // The label (a value that maps up to the types array).
        var label_type = post.innerHTML.match(/^\d+ (.+?) ago$/)[1];
      }
      catch(e) {
        // If either of the matches fail, it's due to an
        // irrelevant link.
        continue;
      }

      // Continue if the label is out of bounds.
      // For instance, 'days' when filtering by 'minutes'.
      if(types.indexOf(label_type) === -1) continue;

      // Continue if the label type matches, but the number
      // is larger than what we're filtering for.
      if(type === label_type && label_number > number) continue;

      // td > div > span > a
      post.parentNode.parentNode.parentNode.className += ' ' + className;
    }
  }