bigdir/app/views/courses/_set_join.js.erb

$("#<%=object_id%>").replaceWith('<%= escape_javascript join_in_course_for_list(course, user) %>');
<% if @state %>
	<% if @state == 0 %>
		alert("加入成功")
	<% else %>
		alert("密码错误")
	<% end %>
<% end %>