Rails中的简单Ajax

My question looks very simple, but strangely nothing that I've tried works.

I just want to load some partials with ajax. I've divided a template into several requests so that the page is loaded one part at a time. Specifically, I would like the #footnotes element to be loaded as an ajax request.

The parent template services/index.html.haml looks like this:

.services
  - @services.each do |service|
    .service= service.name
      #footnotes 

Once the #footnotes element loads, I'd like to launch an ajax call that would load services/_footnotes.html.haml into it.

Here's services/_footnotes.html.haml:

- @footnotes.each do |footnote|
  .footnote= footnote

In ServicesController there's an action that hopefully should render my services/_footnotes.html.haml:

  def footnotes
    stop_id = params[:stop_id]
    service_ids = params[:service_ids].split(/,/)
    @footnotes = ServicesHelper.generate_footnotes(service_ids, stop_id)
    respond_to do |format|
      format.html
      format.json { render json: @footnotes }
    end
  end

I've tried some javascript solutions from various answers that I've read. One of the javascript solutions I've tried and failed with was:

$("#services").ready(function () {
    $(".service").each(function(index, element) {
        var stop_id = $("#stop_id").data("stopid");
        var service_ids = $(element).data("serviceids");
        $("#footnotes", element).getJson("/stops/" + stop_id + "/services/" + service_ids + "/footnotes");
    });
});

This particular solution generates the error Object [object Object] has no method 'getJson'.

It seems that I'm failing to grasp how this really works. What am I doing wrong? What's missing?

It is

$.getJSON

and NOT getJson

So,

$.getJSON("your-json-url-here", function(data) {
    //Do stuff on data!
});

See here: jquery getJSON