First:
<%=form_tag books_path, class: "form-inline", method: :get do %>
<div class="form-group">
<%= text_field_tag :query, params[:query], class: "form-control" %>
<%= submit_tag "Search", class: "btn btn-primary" %>
<% if params[:query].present? %>
<%= link_to "clear", books_path %>
<% end %>
</div>
Second:
<%= javascript_include_tag "//cdnjs.cloudflare.com/ajax/libs/typeahead.js/0.9.3/ typeahead.min.js" %>
Third:
<%= form_tag books_path, class: "form-inline", method: :get do %>
<div class="input-group input-group-lg" >
<% if params[:query].present? %>
<div class="input-group-btn">
<%= link_to "clear", books_path, class: "btn btn-default" %>
</div>
<%= text_field_tag :query, params[:query], class: "form-control", id: "book_search", autocomplete: "off" %>
<div class="input-group-btn">
<%= submit_tag "Search", class: "btn btn-primary" %>
</div>
<% end %>
</div>
You can always verify it here - http://html2slim.herokuapp.com/
Enjoy.