has_many and accepts_nested_attributes_for with nested forms and jquery/ajax

I'm trying to create a nested form where there is a "+" button which adds fields via jquery and ajax. I am doing it adding a step at once, so untill now I am able to add a simple text pushing the "+" button, but, as I have just said, I want to add some fields.

I have the followings:

new.html.erb

<h1>New Campaign</h1>

<%= form_for @campaign, html: { multipart: true } do |f| %>

  ....

  <div class="goods">
    <%= render "goods/good", f: f, child_index: Time.now.to_i %>
  </div>

  <div class="actions">
    <%= link_to '+', add_good_row_path(params[:campaign]=@campaign, params[:f] = f), remote: true, class: 'btn btn-large btn-success' %>
    <%= f.submit 'Crea', class: 'btn btn-large btn-warning' %>
  </div>

<% end %>

goods/_good.html.erb

<%= f.fields_for :goods, @campaign.goods.build, child_index: child_index do |good| %>

  <%= good.text_field :name, placeholder: 'Nome' %>

  <%= good.text_area :description, placeholder: 'Descrizione' %>

  <%= good.text_field :cost, placeholder: 'Costo' %>

<% end %>

campaigns_controller.rb

class CampaignsController < ApplicationController

  ....

  def add_good_row
    respond_to do |format|
      format.js
    end
  end

end

add_good_row.js.erb

$('.goods').append("hello");

I think that I understood the problem, it is to pass a f variable, a @campaign variable and a child_index to the partial, but how can I do that via jquery?

Hope I was clear...