redmine/app/views/imports/run.js.erb

$('#import-progress').progressbar({value: <%= @current.to_i %>});
$('#progress-label').text("<%= @current.to_i %> / <%= @import.total_items.to_i %>");

<% if @import.finished? %>
window.location.href='<%= import_path(@import) %>';
<% else %>
$.ajax({
  url: '<%= import_run_path(@import, :format => 'js') %>',
  type: 'post'
});
<% end %>