我正在尝试使用 jQuery datepicker 函数，但收到错误Uncaught type error: $(...).datepicker() is not a function。我检查了我的文件，没有看到对 jQuery 的双重引用或文件顺序不正确application.js。有人可以帮忙指出可能是什么问题吗？
application.html.erb
<!DOCTYPE html>
<html>
<head>
<%= javascript_include_tag 'application' %>
<title>MyApp</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- CSS/Bootstrap -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" crossorigin="anonymous">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap-theme.min.css" integrity="sha384-fLW2N01lMqjakBkx3l/M9EahuwpSfeNvV63J5ezn3uZzapT0u7EYsXMjQV+0En5r" crossorigin="anonymous">
<%= stylesheet_link_tag 'application' %>
<%= csrf_meta_tags %>
<!-- -->
</head>
<body>
<%= render partial: "shared/top_info" %>
<%= yield %>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js" integrity="sha384-0mSbJDEHialfmuBBQP6A4Qrprq5OVfW37PRR3j5ELqxss1yVqOtnepnHVP9aJ7xS" crossorigin="anonymous">
</script>
<!-- -->
</body>
</html>
应用程序.js
//= require jquery
//= require jquery_ujs
//= require ahoy
//= require_tree .
$('#customer_drop_off_date').datepicker();
html.erb
<% form_tag('/post') do %>
<%= text_field_tag(:customer_drop_off_date) %>
<% end %>
Gemfile
source 'https://rubygems.org'
gem 'rails', '4.2.6'
gem 'pg', '~> 0.15'
gem 'uglifier', '>= 1.3.0'
gem 'jquery-rails'
gem 'jbuilder', '~> 2.0'
gem 'sprockets'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'bcrypt', '~> 3.1.7'
gem 'devise'
gem 'figaro'
gem 'paperclip', '~> 5.0.0.beta1'
gem 'ahoy_matey'
gem 'geocoder'
group :development, :test do
gem "pry"
gem "pry-rails"
gem "pry-stack_explorer"
gem "pry-byebug"
gem 'byebug'
end
group :development do
gem 'web-console', '~> 2.0'
gem 'spring'
end
