survey/app/views/admin/surveys/index.html.erb

<%=  render_filter @filter_fields, "index_table" %>
<span id="index_table">
  <%= render 'index'%>
</span>

<%= render 'layouts/delete_modal', delete_options: @delete_options %>

<div id="downloadModal" data-backdrop="static" class="modal hide fade" tabindex="-1" role="dialog" aria-labelledby="downloadModalLabel" aria-hidden="true">
  <div class="modal-header">
    <h3 id="downloadModalLabel">Download</h3>
  </div>
  <div class="modal-body">
    <p id="wait-zone" style="text-align: center;">
    	Please wait while we prepare your download. This may take a while.
    	<br />
    	<img src="/assets/spin.gif" />
    </p>
    <p id="link-zone" style="display: none; text-align: center;">
      Please click the link below to download.
      <br />
      <a href="" id="download-link" target="_blank">Download</a>
    </p>
  </div>
  <div class="modal-footer">
    <button class="btn" id="modal-close-btn" style="display:none;" data-dismiss="modal" aria-hidden="true">Close</button>
  </div>
</div>
<script type="text/javascript" src="/assets/lib/process.manager.js"></script>
<script type="text/javascript">

  var downloadModal = $("#downloadModal"),
    checkForThread = null,
    waitZone = $("#wait-zone"),
    linkZone = $("#link-zone"),
    downloadLink = $("a#download-link"),
    modalBtn = $("#modal-close-btn"),
    processManager = new ProcessManager();

  $(document).on("click", ".export-xls", function(){
    var link = $(this).attr("href"),
        title = null,
        id = $(this).data("survey-id");
    
    linkZone.hide();    
    waitZone.show();
    modalBtn.hide();
    $.ajax({
      url : link,
      type : "get",
      dataType : "json"
    }).done(function(data){
      title = data.title;
      checkForThread = new Process(function(){
        $.ajax({
          url : "/admin/surveys/checkforthread",
          type : "get",
          data : {"survey_id" : id, "survey_title" : title},
          dataType : "json"
        }).done(function(data){
          if(!data.status){
            downloadLink.attr("href", "/uploads/survey_export/" + id + "/" + title + ".xlsx");
            waitZone.hide();
            linkZone.show();
            modalBtn.show();
            checkForThread.kill();
          }
        })
      })
      checkForThread.setTimeInterval(1000);
      checkForThread.setRepeat(Process.CONSTANTS.REPEAT_INFINITE);
      processManager.queue(checkForThread);
    })
    downloadModal.modal("show");
    return false;
  })

</script>