A Lift response transformer and some CoffeeScript helpful for facilitating cross-domain AJAX requests in Lift.

gistfile1.scala

// If we receive a jQuery JSONP call and we don't call the callback, add in a bogus
// call to the callback function.
LiftRules.responseTransformers.append { response =>
  response.toResponse match {
    case resp @ InMemoryResponse(data, headers, _, _) =>
      {
        for(callback <- S.param("callback")) yield {
          val dataStr = new String(data)

          if (! dataStr.contains(callback)) {
            val updatedData = dataStr + "\n" + callback + "();"
            val updatedHeaders = headers.collect {
              case (headerName, value) if headerName == "Content-Length" =>
                (headerName, updatedData.length.toString)

              case otherHeader => otherHeader
            }

            resp.copy(data = updatedData.getBytes("UTF-8"), headers = updatedHeaders)
          } else {
            resp
          }
        }
      } openOr {
        resp
      }

    case _ =>
      response
  }
}

gistfile2.coffee

window.liftAjax.lift_actualAjaxCall = (data, version, onSuccess, onFailure) ->
  hostnamePrefix = ""

  # Replace the following with values appropriate for your production hostname.
  if window.location.hostname == "anchortab.com"
    hostnamePrefix = "https://anchortab.com"

  jQuery.ajax
    url : hostnamePrefix + liftAjax.addPageNameAndVersion("/ajax_request/", version),
    data : data,
    dataType : "jsonp",
    success : onSuccess,
    error : onFailure,
    crossDomain: true