016. form 表单中下拉选项改变，表单自动提交 onchange & javascript_tag - cwy007/tips-and-skills GitHub Wiki

<%= form_tag store_index_path, method: :get, class: "locale" do %>
  <%= select_tag 'set_locale',
    options_for_select(LANGUAGES, I18n.locale.to_s),
    onchange: 'this.form.submit()' %>

  <!-- 当浏览器没有打开js时，会显示这个送出按钮 -->
  <%= submit_tag 'submit' %>

  <!-- 隐藏这个送出按钮 -->
  <%= javascript_tag "$('.locale input').hide()" %>
<% en

source：agile web development with rails ---book