AJAX loading of new items in Lift (with Non-AJAX fallback)

EndlessList.scala

class EndlessList {
  /**
   * Gets a "page" (e.g., 10 items) of content entities from the database.
   */
  def getPage(page: Int): (Seq[Content], Boolean) = {
    val realPage: Int = if (page < 1) 1 else page
    val limit = 10
    val contents = Content.findAll(
      (/* conditions */),
      Limit(limit + 1),
      Skip((realPage - 1) * limit))
    // actual contents, hasNext
    (contents.take(limit), contents.size > limit)
  }

  /**
   * Given a list of content items, compute the CSS selector to
   * display them.
   */
  def renderPage(contents: Seq[Content]): CssSel = {
    ".content" #> contents.map(c => {
      ".title" #> c.title.is /* &
        other CSS selectors */
    })
  }

  def render = {
    val myUri = S.uri
    val urlPageNo = S.param("page").flatMap(asInt).getOrElse(1)
    var ajaxPageNo = urlPageNo

    // *initially*, we render the HTML as determined by the urlPage
    val initPageData = getPage(urlPageNo)

    /**
     * This is called to insert another page of items to the list.
     */
    def insertPage = {
      // get the next page
      ajaxPageNo += 1
      val thisPage = getPage(ajaxPageNo)
      // render and append to page
      val tmpl = Templates("templates-hidden" :: "_contentblock" :: Nil)
      val html = tmpl.map(t => renderPage(thisPage._1).apply(t))
      AppendHtml("blocks", html.getOrElse(NodeSeq.Empty)) &
        (if (thisPage._2)
        // if there is a next page, update the link
          (JqId("nextlink") ~> JqAttr("href", myUri + "?page=" + (ajaxPageNo + 1))).cmd
        else {
          // if not, disable the link
          (JqId("nextlink") ~> JqAttr("href", myUri + "?page=" + (ajaxPageNo))).cmd &
            (JqId("nextlink") ~> JsFunc("parent") ~> JsFunc("addClass", "disabled")).cmd
        })
    }

    renderPage(initPageData._1) &
    ".pager" #> {
      ".previous" #> {
        // the "previous" link is only present on pages 2 and higher and
        //  is always a static link to the page before
        if (urlPageNo > 2) {
          "a [href]" #> (S.uri + "?page=" + (urlPageNo - 1)) &
            "a [rel]" #> "prev" &
            "a *" #> "Previous"
        } else if (urlPageNo == 2) {
          "a [href]" #> (S.uri) &
            "a [rel]" #> "prev" &
            "a *" #> "Previous"
        } else {
          ".previous" #> NodeSeq.Empty
        }
      } &
        ".next" #> {
          // in a JS-enabled client, this will load the next page,
          //  non-JS-enabled clients will simply follow the link
          if (initPageData._2) {
            "a" #> SHtml.a(insertPage _, "Next", ("rel" -> "next")) andThen
              "a [href]" #> (myUri + "?page=" + (urlPageNo + 1))
          } else {
            ".next" #> NodeSeq.Empty
          }
        }
    }
  }
}

list.html

<div class="lift:surround?with=default;at=content">
  <div class="lift:EndlessList?eager_eval=true">
    <div id="blocks">
      <div class="lift:embed?what=_contentblock"></div>
    </div>
    <div>
      <ul class="pager">
        <li class="previous"><a href="#">Previous</a></li>
        <li class="next"><a id="nextlink" href="#">Next</a></li>
      </ul>
    </div>
  </div>
</div>