link_to :confirm displays popup twice

Question

This tag with rails 3

<%= link_to \'Destroy\', item, :method => :delete,:confirm=>\'Are you sure?\' %>

produces this html

Answer 1

Delete:

//= require jquery
//= require jquery_ujs
//= require_tree .

from app/assets/javascripts/application.js. Despite of been commented it loads these js files. It works for me.