Cannot use javascript parameter with rails

I need to get the value of a parameter in a javascript code and pass it on to a rails partial view but it won't let me do that. Here is what I have:

<div id="myCarousel" data-carousel-3d>
  <% @users.each do |user| %>
    <input type="image" src="/assets/<%= user.location %>"  data-toggle="modal" data-target="#modal-1" />                   
  <% end %>                                     
</div>
<script>
  $('#myCarousel').on('select', function (evt, index) {
    var myHtml = "<\%= escape_javascript (\"#{render :partial => 'share', :locals => { :user_location => ";
                    myHtml = myHtml.concat(index);
                    myHtml = myHtml.concat(".jpg }}");
    $("#modal-test").append("<%= escape_javascript(  myHtml  ).html_safe %>");                  
  });
</script>

This code will give me and error message:

undefined local variable or method `myHtml' for #< :0x007fe1d472cd70>

I tried to concat the whole string into myHtml and do an append(myHtml) but this way it will not render the erb code in the page. It shows as a string.

We have a carousel displaying images and the ultimate goal is when the user clicks on one of the images, we show a modal window with the image they clicked in there.

Any ideas?