title: Sprockets::FileNotFound in StaticPages#home
body: <p>i'm working on Michael Hartl's ruby on rails tutorial and i've run into a problem that i haven't been able to fix for days.  </p>
  
  <p>when trying to load the page, chrome reads:</p>
  
  <pre><code>Sprockets::FileNotFound in StaticPages#home
  Showing /Users/azimmer/rails_projects/sample_app/app/views/layouts/application.html.erb where line #7 raised:
  
  couldn't find file 'jquery'
    (in /Users/azimmer/rails_projects/sample_app/app/assets/javascripts/application.js:13)
  Extracted source (around line #7):
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        &lt;title&gt;&lt;%= full_title(yield(:title)) %&gt;&lt;/title&gt;
        &lt;%= stylesheet_link_tag "application", media: "all",
                                               "data-turbolinks-track" =&gt; true %&gt;
        &lt;%= javascript_include_tag "application", "data-turbolinks-track" =&gt; true %&gt;
        &lt;%= csrf_meta_tags %&gt;
        &lt;%= render 'layouts/shim' %&gt;
        &lt;/head&gt;
  
  Rails.root: /Users/azimmer/rails_projects/sample_app
  </code></pre>
  
  <p>here is my gemfile: </p>
  
  <pre><code>source 'https://rubygems.org'
  ruby '2.0.0'
  #ruby-gemset=railstutorial_rails_4_0
  
  gem 'rails', '4.0.2'
  gem 'bootstrap-sass', '2.3.2.0'
  gem 'bcrypt-ruby', '3.1.2'
  
  group :development, :test do
    gem 'sqlite3', '1.3.8'
    gem 'rspec-rails', '2.13.1'
  end
  
  group :test do
    gem 'selenium-webdriver', '2.35.1'
    gem 'capybara', '2.1.0'
  
  gem 'sass-rails', '4.0.2'
  gem 'uglifier', '2.1.1'
  gem 'coffee-rails', '4.0.1'
  gem 'jquery-rails', '2.3.0'
  gem 'turbolinks', '1.1.1'
  gem 'jbuilder', '1.0.2'
  gem 'factory_girl_rails', '4.2.1'
  
  end
  
  group :doc do
    gem 'sdoc', '0.3.20', require: false
  end
  
  group :production do
    gem 'pg', '0.15.1'
    gem 'rails_12factor', '0.0.2'
  end
  </code></pre>
  
  <p>and here is my application.html.erb file:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;title&gt;&lt;%= full_title(yield(:title)) %&gt;&lt;/title&gt;
      &lt;%= stylesheet_link_tag "application", media: "all",
                                             "data-turbolinks-track" =&gt; true %&gt;
      &lt;%= javascript_include_tag "application", "data-turbolinks-track" =&gt; true %&gt;
      &lt;%= csrf_meta_tags %&gt;
      &lt;%= render 'layouts/shim' %&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;%= render 'layouts/header' %&gt;
      &lt;div class="container"&gt;
        &lt;%= yield %&gt;
        &lt;%= render 'layouts/footer' %&gt;
        &lt;%= debug(params) if Rails.env.development? %&gt;
      &lt;/div&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>my application.js file is totally untouched.  i have tried everything from adding gem rubyracer, to editing the runtimes.rb file in execjs recommended on another thread.  i'm considering just starting over from scratch in order to get everything to work, at least in that case i would relearn a lot of what i've learned, but i'm hoping someone can at least help me figure out what is going on here.</p>
  
  <p>thanks a bunch for your help!</p>
  
  <p>cheers,
  alex</p>
  
  <p>EDIT</p>
  
  <p>it works if i change the line from</p>
  
  <pre><code>&lt;%= javascript_include_tag 'application', "data-turbolinks-track" =&gt; true %&gt;
  </code></pre>
  
  <p>to</p>
  
  <pre><code>&lt;%= javascript_include_tag :default, "data-turbolinks-track" =&gt; true %&gt;
  </code></pre>
  
  <p>could anyone explain what this means?  and how making that change might affect my application in a negative way?  thank you for the help!</p>