Sprockets is an easy solution to managing large JavaScript codebases by letting you structure it, bundle it with related assets, and consolidate it as one single file, with pre-baked command-line tooling, CGI front and Rails plugin. It's a framework-agnostic open-source solution that makes for great serving performance while helping you structure and manage your codebase better.

1. Sprockets
You’ve got tons of JavaScript.
Time to do something about it.
Christophe Porteneuve
JSConf.eu 2009

2. Hi, I’m Christophe
• I’m 32 and I live in Paris, France
• I use Rails all day at work
• I’m a Prototype Core member
• I wrote Prototype and script.aculo.us
(“The Bungee Book”)
• I’m glad to be here!

3. The problem

4. The problem
• JavaScript is the next big language…

5. The problem
• JavaScript is the next big language…
• It’s already getting big, codewise!

6. The problem
• JavaScript is the next big language…
• It’s already getting big, codewise!
• Many apps have countless JS files

7. The problem
• JavaScript is the next big language…
• It’s already getting big, codewise!
• Many apps have countless JS files
• Loading → lots of requests → latence

8. The problem
• JavaScript is the next big language…
• It’s already getting big, codewise!
• Many apps have countless JS files
• Loading → lots of requests → latence
• Or you could maintain one big file…

9. The problem
• JavaScript is the next big language…
• It’s already getting big, codewise!
• Many apps have countless JS files
• Loading → lots of requests → latence
• Or you could maintain one big file…
• …which sucks

10. The solution

11. The solution
• You want to split your JS code in neat files
and folders!

12. The solution
• You want to split your JS code in neat files
and folders!
• You want some structure, dammit!

13. The solution
• You want to split your JS code in neat files
and folders!
• You want some structure, dammit!
• But you want to serve just one file!

14. The solution
• You want to split your JS code in neat files
and folders!
• You want some structure, dammit!
• But you want to serve just one file!
• Enter Sprockets

15. So many cool things…

16. So many cool things…
• Use require directives and load paths to
structure your source

17. So many cool things…
• Use require directives and load paths to
structure your source
• Preprocess constants!

18. So many cool things…
• Use require directives and load paths to
structure your source
• Preprocess constants!
• Create “JS plugins,” complete with related
CSS/image assets, bundle them and
distribute them easily

19. Getting organized

20. Getting organized
…
//= require "lang"
//= require "ajax"
//= require "dom"

21. Getting organized
//= require "dom/dom"
//= require "dom/selector"
//= require "dom/form"
//= require "dom/event"
Element.addMethods();
…
//= require "lang"
//= require "ajax"
//= require "dom"

22. Getting organized
//= require "ajax/ajax"
//= require "ajax/responders"
//= require "ajax/base"
//= require "ajax/request"
//= require "ajax/response"
//= require "ajax/updater"
//= require "ajax/periodical_updater"
//= require "dom/dom"
//= require "dom/selector"
//= require "dom/form"
//= require "dom/event"
Element.addMethods();
…
//= require "lang"
//= require "ajax"
//= require "dom"

23. The load path
Sprockets has a load path, much like C’s or
Ruby’s

24. The load path
Sprockets has a load path, much like C’s or
Ruby’s
Using the load path:
//= require <coolobj>
//= require <coollib/coolobj>

25. The load path
Sprockets has a load path, much like C’s or
Ruby’s
Using the load path:
//= require <coolobj>
//= require <coollib/coolobj>
Using paths relative to the current file:
//= require "coolobj"
//= require "subdir/coolobj"

26. Constants FTW!
Put a constants.yml file somewhere in your
load path
• It’s a YAML file
• Heard of YAML, right?
• Super simple yet powerful

27. Constants for you

28. Constants for you

29. Constants for you
PROTOTYPE_VERSION: 1.6.1_rc3

30. Constants for you
PROTOTYPE_VERSION: 1.6.1_rc3
var Prototype = {
Version: '<%= PROTOTYPE_VERSION %>',
Browser: (function(){
…

31. Bundling assets
//= require "color"
//= provide "../assets"
Because you require <color_picker>,
Sprockets can copy the assets to your asset root
(somewhere inside your document root)

32. I can haz?
• It’s a Ruby gem
• You don’t need to know Ruby though
• You do need Ruby and Rubygems installed

33. I can haz?
• It’s a Ruby gem
• You don’t need to know Ruby though
• You do need Ruby and Rubygems installed
$ sudo gem install --remote sprockets

34. As a command-line tool…
$ sprocketize
Usage: sprocketize [options] filename [filename ...]
-C, --directory=DIRECTORY Change to DIRECTORY before doing anything
-I, --include-dir=DIRECTORY Adds the directory to the Sprockets load path
-a, --asset-root=DIRECTORY Copy provided assets into DIRECTORY
…
-h, --help Shows this help message
-v, --version Shows version

35. As a command-line tool…
$ sprocketize
Usage: sprocketize [options] filename [filename ...]
-C, --directory=DIRECTORY Change to DIRECTORY before doing anything
-I, --include-dir=DIRECTORY Adds the directory to the Sprockets load path
-a, --asset-root=DIRECTORY Copy provided assets into DIRECTORY
…
-h, --help Shows this help message
-v, --version Shows version
$ sprocketize -I src -a dist src/application.js > dist/javascripts/application.js

36. Within Ruby code…

37. Within Ruby code…
require 'rubygems'
require 'sprockets'
secretary = Sprockets::Secretary.new(
:asset_root => "public",
:load_path => ["vendor/sprockets/*/src", "vendor/plugins/*/javascripts"],
:source_files => ["app/javascripts/application.js", "app/javascripts/**/*.js"]
)
concatenation = secretary.concatenation
concatenation.save_to("public/sprockets.js")
secretary.install_assets

38. As a CGI script…
Say you have this tree

39. As a CGI script…
Say you have this tree
:load_path:
- javascripts
- vendor/sprockets/*/src
:source_files:
- javascripts/mysite.js
- javascripts/*.js
:output_file: public/sprockets.js
So you write this
sprockets.yml

40. As a CGI script…
<VirtualHost *:80>
ServerName www.sprocketsrule.com
DocumentRoot "/var/webapps/sprocketsrule/public"
<Directory "/var/webapps/sprocketsrule/public">
Options +ExecCGI +FollowSymLinks
AddHandler cgi-script .cgi
RewriteEngine on
RewriteCond /sprockets.js !-f
RewriteRule ^sprockets.js /nph-sprockets.cgi [P,L]
SetEnv sprockets_generate_output_file true
</Directory>
</VirtualHost>
<script type="text/javascript" src="/sprockets.js"></script>

41. As a CGI script…
<VirtualHost *:80>
ServerName www.sprocketsrule.com
DocumentRoot "/var/webapps/sprocketsrule/public"
<Directory "/var/webapps/sprocketsrule/public">
Options +ExecCGI +FollowSymLinks
Provided in the ext/
AddHandler cgi-script .cgi directory of Sprockets
RewriteEngine on
RewriteCond /sprockets.js !-f
RewriteRule ^sprockets.js /nph-sprockets.cgi [P,L]
SetEnv sprockets_generate_output_file true
</Directory>
</VirtualHost>
<script type="text/javascript" src="/sprockets.js"></script>

42. As a CGI script…
<VirtualHost *:80>
T
ServerName www.sprocketsrule.com
A
DocumentRoot "/var/webapps/sprocketsrule/public"
N E
<Directory "/var/webapps/sprocketsrule/public">
Options +ExecCGI +FollowSymLinks
Provided in the ext/
AddHandler cgi-script .cgi directory of Sprockets
RewriteEngine on
RewriteCond /sprockets.js !-f
RewriteRule ^sprockets.js /nph-sprockets.cgi [P,L]
SetEnv sprockets_generate_output_file true
</Directory>
</VirtualHost>
<script type="text/javascript" src="/sprockets.js"></script>

43. …or use Rails!

44. …or use Rails!
$ script/plugin install git://github.com/sstephenson/sprockets-rails.git

45. …or use Rails!
$ script/plugin install git://github.com/sstephenson/sprockets-rails.git
ActionController::Routing::Routes.draw do |map|
SprocketsApplication.routes(map)
# ...
end

46. …or use Rails!
$ script/plugin install git://github.com/sstephenson/sprockets-rails.git
ActionController::Routing::Routes.draw do |map|
SprocketsApplication.routes(map)
# ...
end
<%= sprockets_include_tag %>

47. …or use Rails!
O M E
S
$ script/plugin install git://github.com/sstephenson/sprockets-rails.git
A W E
ActionController::Routing::Routes.draw do |map|
SprocketsApplication.routes(map)
# ...
end
<%= sprockets_include_tag %>

48. Hey, like to squeeze?

49. Hey, like to squeeze?
Just because it’s one big file
doesn’t mean it’s one small file
(that didn’t come out right)

50. YUI Compressor

51. YUI Compressor
• Arguably the best source shrinker out
there

52. YUI Compressor
• Arguably the best source shrinker out
there
• 100% safe yet full of optimizations

53. YUI Compressor
• Arguably the best source shrinker out
there
• 100% safe yet full of optimizations
• Better than JSMin, ShrinkSafe, Packer…

54. YUI Compressor
• Arguably the best source shrinker out
there
• 100% safe yet full of optimizations
• Better than JSMin, ShrinkSafe, Packer…
• Does not obfuscate (which is good)

55. YUI Compressor
• Arguably the best source shrinker out
there
• 100% safe yet full of optimizations
• Better than JSMin, ShrinkSafe, Packer…
• Does not obfuscate (which is good)
• Distributed as a JAR file

56. The gem wrapper

57. The gem wrapper
$ sudo gem install --remote yui-compressor

58. The gem wrapper
$ sudo gem install --remote yui-compressor
compressor = YUI::JavaScriptCompressor.new(:munge => true)
compressor.compress('(function () { var foo = {}; foo["bar"] = "baz"; })()')
# => '(function(){var a={};a.bar="baz"})();'

59. The gem wrapper
$ sudo gem install --remote yui-compressor
compressor = YUI::JavaScriptCompressor.new(:munge => true)
compressor.compress('(function () { var foo = {}; foo["bar"] = "baz"; })()')
# => '(function(){var a={};a.bar="baz"})();'
YUI::JavaScriptCompressor.new(
:java => "/usr/bin/java",
:jar_file => "/path/to/my/yuicompressor-2.4.2.jar"
)
Full compressor support: CSS too, options aplenty…

60. A match made in heaven
# config/sprockets.yml
:asset_root: public
:load_path:
- app/javascripts
- vendor/sprockets/*/src
- vendor/plugins/*/javascripts
:source_files:
- app/javascripts/application.js
- app/javascripts/**/*.js
:compress:
:munge: true
Warning: not in master gems yet. See my forks.
(incidentally, in production use at http://letsfreckle.com)

61. So what’s left?

62. So what’s left?
• Tweak your assets HTTP server: GZip and
cache the heck on the client side

63. So what’s left?
• Tweak your assets HTTP server: GZip and
cache the heck on the client side
• If necessary, offload mainstream libs serving
to Google

64. Apache config you’ll love
LoadModule deflate_module /usr/lib/apache2/modules/mod_deflate.so
LoadModule headers_module /usr/lib/apache2/modules/mod_headers.so
LoadModule expires_module /usr/lib/apache2/modules/mod_expires.so
AddOutputFilterByType DEFLATE text/html text/plain text/xml application/xml
↪application/xhtml+xml text/javascript text/css application/x-javascript
ExpiresActive On
ExpiresByType image/gif "access plus 5 years"
ExpiresByType image/png "access plus 5 years"
ExpiresByType image/jpeg "access plus 5 years"
ExpiresByType text/javascript "access plus 5 years"
ExpiresByType application/x-javascript "access plus 5 years"
ExpiresByType text/css "access plus 5 years"
Header unset ETag
FileETag None
Header add Cache-Control "public"
http://javascriptrocks.com/performance/

65. Numbers!
No opti. All opti.
Bytes 292.520 30.919
HTTP requests 3 / 38* 1
Load time (unprimed) 1900+456ms 400+43ms
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

66. Numbers!
No opti. All opti.
Bytes 292.520 30.919
HTTP requests 3 / 38* 1
Load time (unprimed) 1900+456ms 400+43ms
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

67. Numbers!
No opti. All opti.
Bytes 292.520 30.919
HTTP requests 3 / 38* 1
Load time (unprimed) 1900+456ms 400+43ms
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

68. Numbers!
No opti. All opti.
Bytes 292.520 30.919
HTTP requests 3 / 38* 1
Load time (unprimed) 1900+456ms 400+43ms
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

69. Numbers!
No opti. All opti.
Bytes 292.520 30.919
HTTP requests 3 / 38* 1
Load time (unprimed) 1900+456ms 400+43ms
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

70. Numbers!
V
No opti. All opti.
Bytes
Y M
HTTP requests
Load time (unprimed)
M
292.520
3 / 38*
1900+456ms
30.919
400+43ms
1
Load time (primed) 1900+76ms 1+41ms
* monolithic vendor scripts / structured source

71. Google Ajax Libraries API

72. Google Ajax Libraries API
• Google hosts most recent versions of
Prototype, jQuery, script.aculo.us,
MooTools, Dojo, Ext Core,YUI…

73. Google Ajax Libraries API
• Google hosts most recent versions of
Prototype, jQuery, script.aculo.us,
MooTools, Dojo, Ext Core,YUI…
• Top-notch serving (e.g. cache-related
headers + GZipping) + CDN

74. Google Ajax Libraries API
• Google hosts most recent versions of
Prototype, jQuery, script.aculo.us,
MooTools, Dojo, Ext Core,YUI…
• Top-notch serving (e.g. cache-related
headers + GZipping) + CDN
• Bonus: if another site loaded it already, your
user doesn’t have to load it for your site!

75. Thank you, Sam.

76. Thank you, Sam.
• Sprockets, Sprockets-Rails and
YUI::Compressor are open-
source stuff by Sam
Stephenson, creator of
Prototype.

77. Thank you, Sam.
• Sprockets, Sprockets-Rails and
YUI::Compressor are open-
source stuff by Sam
Stephenson, creator of
Prototype.
• http://github.com/sstephenson

78. Thank you, Sam.
• Sprockets, Sprockets-Rails and
YUI::Compressor are open-
source stuff by Sam
Stephenson, creator of
Prototype.
• http://github.com/sstephenson
• http://github.com/tdd

80. Thank you!
Any questions?
Christophe Porteneuve
tdd@tddsworld.com
JSConf.eu 2009