/
index.html
896 lines (796 loc) · 34.6 KB
/
index.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=UTF-8">
<meta http-equiv="X-UA-Compatible" content="chrome=1">
<title>Jammit: Industrial-strength asset packaging for Rails</title>
<style>
body {
font-size: 16px;
line-height: 24px;
background: #fafcff;
color: #192535;
font-family: Arial;
font-family: "Palatino Linotype", "Book Antiqua", Palatino, FreeSerif, serif;
}
div.container {
width: 720px;
margin: 50px 0 50px 50px;
}
p, li {
margin: 16px 0 16px 0;
width: 550px;
}
a, a:visited {
padding: 0 2px;
text-decoration: none;
background: #cadaea;
color: #192535;
}
a:active, a:hover {
color: #000;
background: #bacada;
}
h1, h2, h3, h4, h5, h6 {
margin-top: 40px;
}
b.header {
font-size: 18px;
}
span.alias {
font-size: 14px;
font-style: italic;
margin-left: 20px;
}
table {
margin: 16px 0; padding: 0;
}
tr, td {
margin: 0; padding: 0;
}
td {
padding: 9px 15px 9px 0;
}
td.definition {
line-height: 18px;
font-size: 14px;
}
code, pre, tt {
font-family: Monaco, Consolas, "Lucida Console", monospace;
font-size: 12px;
line-height: 18px;
color: #294555;
}
code {
margin-left: 20px;
}
pre {
font-size: 12px;
padding: 2px 0 2px 12px;
border-left: 6px solid #99aabb;
margin: 0px 0 30px;
}
#diagram {
margin: 20px 0 0 0;
}
</style>
</head>
<body>
<div class="container">
<p>
<img src="jammit-logo.png" width="276" height="84" alt="Jammit">
</p>
<p>
<a href="https://github.com/documentcloud/jammit/">Jammit</a> is an
industrial-strength asset packaging library for <b>Rails</b>, providing
both the CSS and JavaScript concatenation and compression
that you'd expect, as well as <b>YUI Compressor</b>, <b>Closure Compiler</b>, and <b>UglifyJS</b>
compatibility, ahead-of-time gzipping, built-in JavaScript template
support, and optional <b>Data-URI / MHTML image and font embedding</b>.
</p>
<p>
<b>Current Version:</b> <a href="https://rubygems.org/gems/jammit/">0.7.0</a>
</p>
<p>
You can report bugs and discuss features on the
<a href="https://github.com/documentcloud/jammit/issues">issues page</a>,
on Freenode in the <tt>#documentcloud</tt> channel,
or send tweets to <a href="https://twitter.com/documentcloud">@documentcloud</a>.
</p>
<p>
<i>Jammit is an open-source component of <a href="https://www.documentcloud.org/">DocumentCloud</a>.</i>
</p>
<h2>Table of Contents</h2>
<p style="line-height: 30px; width: 650px;">
<a href="#installation">Installation</a> |
<a href="#configuration">Configuration</a> |
<a href="#usage">Usage</a> |
<a href="#compressors">YUI, Closure & UglifyJS</a> |
<a href="#precaching">Precaching Assets</a> <br>
<a href="#expires">Expires Headers</a> |
<a href="#embedding">Embedding Assets</a> |
<a href="#jst">JavaScript Templates</a> |
<a href="#changes">Changes</a>
</p>
<h2>Links</h2>
<p style="line-height: 30px;">
<a href="https://github.com/documentcloud/jammit">Source Code</a> |
<a href="https://documentcloud.github.io/jammit/doc/">Internal Docs</a> |
<a href="http://jashkenas.s3.amazonaws.com/misc/jammit_example/normal.html">Image Embedding Example</a>
</p>
<h2 id="installation">Installation</h2>
<ol>
<li>
Grab the gem:<br>
<tt>gem install jammit</tt>
</li>
<li>
Add the gem to Rails' <b>environment.rb</b> inside of the initializer:<br>
<tt>config.gem "jammit"</tt>
</li>
<li>
<p>
If you're using <b>Rails 3 or higher</b>, you're done! Jammit routes
(under <b>/assets</b> by default) will be loaded automatically into
your app.
</p>
<p>
If you're using <b>Rails 2</b>, edit <b>config/routes.rb</b> to give
Jammit routes for dynamic asset packaging and caching.
</p>
<pre>
ActionController::Routing::Routes.draw do |map|
...
Jammit::Routes.draw(map)
...
end</pre>
</li>
</ol>
<p>
<i>Note: If you don't already have the
<a href="https://github.com/sstephenson/ruby-yui-compressor">ruby-yui-compressor</a>,
<a href="https://github.com/documentcloud/closure-compiler">closure-compiler</a> or
<a href="https://github.com/lautis/uglifier">uglifier</a>
gems installed, downloading may take a minute — the jar files together
weigh in at 5 megabytes.</i>
</p>
<h2 id="configuration">Configuration</h2>
<p>
Jammit uses the <b>config/assets.yml</b> YAML configuration file to define
packages and to set extra options. A package is an ordered set of directory glob
rules that will be expanded into a unique list of files. An example of
a complete <b>assets.yml</b> follows:
</p>
<pre>
embed_assets: on
javascripts:
workspace:
- public/javascripts/vendor/jquery.js
- public/javascripts/lib/*.js
- public/javascripts/views/**/*.js
- app/views/workspace/*.jst
stylesheets:
common:
- public/stylesheets/reset.css
- public/stylesheets/widgets/*.css
workspace:
- public/stylesheets/pages/workspace.css
empty:
- public/stylesheets/pages/empty.css</pre>
<p>
There are a number of extra configuration options that you may add to the
<b>assets.yml</b> configuration file to customize the way Jammit behaves.
Here's an <a href="https://gist.github.com/667693">example configuration file</a>
using all of the possible options. The meaning of the options and their
default values are listed below. Don't be bewildered by the length of the
list — none of the options are required, they just give you fine-grained
control over how your packages are generated.
</p>
<table>
<tr>
<td><b>package_assets</b></td>
<td><tt>on | off | always</tt></td>
<td class="definition">
Defaults to <b>on</b>, packaging and caching assets in every environment
but <tt>development</tt> and <tt>test</tt>.
Never packages when <b>off</b>, always packages when <b>always</b>.
</td>
</tr>
<tr>
<td><b>embed_assets</b></td>
<td><tt>on | off | datauri</tt></td>
<td class="definition">
Defaults to <b>off</b>. When <b>on</b>, packages and caches Data-URI
and MTHML variants of your stylesheets, with whitelisted images
embedded inline. Using <b>datauri</b> serves embedded images only
to browsers that support Data-URIs, and serves unmodified stylesheets
to Internet Explorer 7 or lower.
</td>
</tr>
<tr>
<td><b>compress_assets</b></td>
<td><tt>on | off</tt></td>
<td class="definition">
Defaults to <b>on</b>. When <b>off</b>, JavaScript and CSS packages
will be left uncompressed (by YUI, Closure, or UglifyJS). Disabling compression is only recommended
if you're packaging assets in development.
</td>
</tr>
<tr>
<td><b>rewrite_relative_paths</b></td>
<td><tt>on | off</tt></td>
<td class="definition">
Defaults to <b>on</b>. When <b>off</b>, relative paths with CSS will be left unchanged.
</td>
</tr>
<tr>
<td><b>gzip_assets</b></td>
<td><tt>on | off</tt></td>
<td class="definition">
Defaults to <b>on</b>. When <b>off</b>, only the plain version of the
asset will be written out, not the <tt>.gz</tt> alternative. Disable this
if you don't plan on configuring your webserver to serve the static
gzip alternatives.
</td>
</tr>
<tr>
<td><b>javascript_compressor</b></td>
<td><tt>yui | closure | uglifier</tt></td>
<td class="definition">
Defaults to <b>yui</b>. The Jammit gem can use either the
<a href="http://developer.yahoo.com/yui/compressor/">YUI Compressor</a>, the
<a href="https://developers.google.com/closure/compiler/">Google Closure Compiler</a>, or
<a href="https://github.com/mishoo/UglifyJS/">UglifyJS</a>
to compress your JavaScript.
</td>
</tr>
<tr>
<td><b>allow_debugging</b></td>
<td><tt>on | off</tt></td>
<td class="definition">
Defaults to <b>on</b>. Leaving it on allows you to pass
<tt>debug_assets=true</tt> as a query parameter, in order to load the
page with uncompressed, unpackaged assets in production.
</td>
</tr>
<tr>
<td><b>template_function</b></td>
<td><tt>on | off | ...</tt></td>
<td class="definition">
The JavaScript function that compiles your JavaScript templates (<b>JST</b>).
Defaults to <b>on</b>, which uses a bundled variant of
<a href="http://ejohn.org/blog/javascript-micro-templating/">Micro-Templating</a>.
Set it to <b>_.template</b> if you use
<a href="http://jashkenas.github.io/underscore/">Underscore.js</a>,
or <b>new Template</b> for
<a href="http://prototypejs.org/">Prototype</a>. Turn it <b>off</b>
to pass through the template strings unaltered.
</td>
</tr>
<tr>
<td><b>template_namespace</b></td>
<td><tt>...</tt></td>
<td class="definition">
By default, all of your compiled templates will be added to a top-level
<b>window.JST</b> object. If you'd like to add them instead to your
own JavaScript namespace, change it to the
object of your choice.
</td>
</tr>
<tr>
<td><b>template_extension</b></td>
<td><tt>...</tt></td>
<td class="definition">
By default, Jammit treats files with a <tt>jst</tt> extension as
JavaScript templates. If you'd prefer to use a different extension, like
<tt>html.mustache</tt>, set the <b>template_extension</b> option.
</td>
</tr>
<tr>
<td><b>package_path</b></td>
<td><tt>...</tt></td>
<td class="definition">
The URL at which packaged assets are cached and made available.
Defaults to <b>assets</b>, but if you already have an existing
AssetsController with a different purpose, you could change it to, say,
<b>packages</b>. <i>(Single directory names only, please.)</i>
</td>
</tr>
<tr>
<td><b>compressor_options</b></td>
<td><tt>...</tt></td>
<td class="definition">
Pass an options hash directly to the underlying JavaScript compressor
to configure it. See the
<a href="http://github.com/sstephenson/ruby-yui-compressor">ruby-yui-compressor</a>,
<a href="http://github.com/documentcloud/closure-compiler">closure-compiler</a>, or
<a href="https://github.com/lautis/uglifier">uglifier</a>
gem documentation for the full list of available options.
</td>
</tr>
<tr>
<td><b>css_compressor_options</b></td>
<td><tt>...</tt></td>
<td class="definition">
Pass an options hash directly to the YUI CSS Compressor.
<a href="http://yui.rubyforge.org/classes/YUI/CssCompressor.html">Available options</a>
are <b>charset</b>, and <b>line_break</b>, which can be used to write
out each CSS rule on a separate line.
</td>
</tr>
</table>
<p>
The contents of <tt>assets.yml</tt> are passed through <b>ERB</b> before
being loaded, in case you find the need to configure Jammit
for different environments.
</p>
<p>
<i>Warning: In <b>Rails 3 and higher</b>, static assets are not served by
default. You either have to configure your webserver to serve static
assets out of</i> <tt>public</tt> <i>(recommended), or set</i>
<tt>config.serve_static_assets = true</tt>
</p>
<h2 id="usage">Usage</h2>
<p>
To access your packages in views, use the corresponding helper. The
helper methods can include multiple packages at once:
</p>
<pre>
<%= include_stylesheets :common, :workspace, :media => 'all' %>
<%= include_javascripts :workspace %></pre>
<p>
In development, no packaging is performed, so you'll see a list of individual
references to all of the JavaScript and CSS files. The <b>assets.yml</b>
configuration file is reloaded on every development request, so you can
change the contents of your packages without needing to restart Rails.
In all other environments, or if <b>package_assets</b> is set to "<b>always</b>",
you'll get tags for the merged packages.
</p>
<p>
If <b>allow_debugging</b> is left on, you'll be able to request the development
version of the assets for any given page, by passing <tt>debug_assets=true</tt>
as a query parameter.
</p>
<p>
You can easily use Jammit within your Rakefile, and other scripts:
</p>
<pre>require 'jammit'
Jammit.package!</pre>
<h2 id="compressors">YUI, Closure & UglifyJS</h2>
<p>
Jammit can be configured to use the
<a href="http://developer.yahoo.com/yui/compressor/">YUI Compressor</a>, the
<a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a>, or
<a href="https://github.com/mishoo/UglifyJS/">UglifyJS</a>
to compress and optimize your JavaScript. (CSS is always run through the
YUI Compressor.) Specify the <b>javascript_compressor</b> to choose either <b>yui</b>,
<b>closure</b>, or <b>uglifier</b> backends. If left blank, Jammit defaults to <b>yui</b>.
</p>
<p>
You can configure the JavaScript compilation by adding <b>compressor_options</b>
to your <b>assets.yml</b>. The <b>compressor_options</b>
will be passed directly to the Gem backend of your chosen compressor. See the
<a href="http://github.com/sstephenson/ruby-yui-compressor">ruby-yui-compressor</a>,
<a href="http://github.com/documentcloud/closure-compiler">closure-compiler</a>, or
<a href="https://github.com/lautis/uglifier">uglifier</a>
gem documentation for all the available options. For example, to configure
the Closure Compiler to use its
<a href="http://code.google.com/closure/compiler/docs/compilation_levels.html">advanced optimizations</a>,
you would add the <b>compilation_level</b>:
</p>
<pre>
javascript_compressor: closure
compressor_options:
compilation_level: "ADVANCED_OPTIMIZATIONS"
</pre>
<p>
Jammit always uses the YUI CSS Compressor to compress CSS files. You can
<a href="http://yui.rubyforge.org/classes/YUI/CssCompressor.html">configure it</a>
by specifying the <b>css_compressor_options</b>, in <b>assets.yml</b>.
</p>
<p>
<i>
<b>Warning:</b> Google's Closure Compiler has been known to choke on certain
already pre-compressed JavaScripts, such as the production version of jQuery.
Using the uncompressed development version is recommended.
</i>
</p>
<h2 id="precaching">Precaching Assets</h2>
<p>
Installing the Jammit gem provides the optional but handy <tt>jammit</tt> command-line utility,
which can be hooked into your deployment process. The <tt>jammit</tt>
command reads in your configuration file, generates all of the defined
packages, and gzips them at the highest compression setting. In order to
serve these static gzipped versions, configure your <b>Nginx</b>
<a href="http://wiki.nginx.org/NginxHttpGzipStaticModule">http_gzip_static_module</a>,
or your <b>Apache</b>
<a href="http://httpd.apache.org/docs/2.0/content-negotiation.html">Content Negotiation MultiViews</a>.
It's also a good idea to have gzip compression turned on for the remainder
of your static assets, including any asset packages that aren't gzipped-in-advance.
Adding <b>Nginx</b>'s
<a href="http://wiki.nginx.org/NginxHttpGzipModule">http_gzip_module</a>
or <b>Apache</b>'s
<a href="http://httpd.apache.org/docs/2.0/mod/mod_deflate.html">mod_deflate</a>
will do the trick.
</p>
<p>
The <tt>jammit</tt> command can be passed options to configure the
path to <b>assets.yml</b>, and the output directory in which all packages
are compiled. Run <tt>jammit --help</tt> to see all of the options. For
speedy builds, <tt>jammit</tt> will check the modification times of your packages
and source files: only the packages that have changed are rebuilt. If you'd
like to force all packages to build, use <tt>jammit --force</tt>.
</p>
<p>
In production, you'll want to run Jammit during deployment, somewhere
in between updating the source and symlinking to the new release. Whether you're
using <a href="http://www.capify.org/index.php/Capistrano">Capistrano</a>,
<a href="http://rubyhitsquad.com/Vlad_the_Deployer.html">Vlad</a>,
or just good 'ol <a href="http://rake.rubyforge.org/">Rake</a>,
it shouldn't be too hard to add a step that calls the <tt>jammit</tt> command.
</p>
<h2 id="expires">Expires Headers</h2>
<p>
To get the fastest page load times for your regular visitors, it's recommended
to set the HTTP Expires header to a date far in the future. You don't need
to worry about clearing the cached assets when you deploy a new release,
because Rails will write out the asset's modification time as part of the URL,
causing browsers to fetch a fresh copy of the asset.
</p>
<p>
If you're using an <b>Nginx</b> webserver, add the following snippet to the
<br><tt>server { ... }</tt> block for your application:
</p>
<pre>
location ~ ^/assets/ {
passenger_enabled on;
expires max;
}</pre>
<p>
If you're using <b>Apache</b>, make sure that
<a href="http://httpd.apache.org/docs/1.3/mod/mod_expires.html">mod_expires</a>
is enabled, and then add the following snippet to the
appropriate <b>VirtualHost</b> section of your configuration,
filling in the path to your deployed application:
</p>
<pre>
ExpiresActive On
<Directory "/path/to/public/assets">
ExpiresDefault "access plus 1 year"
</Directory></pre>
<p>
If for any reason (multiple physical servers, rsync-only deploys) you don't
wish to rely on modification times for cache expiry, Jammit uses the
standard Rails helpers to generate URLs, and will respect
the <tt>RAILS_ASSET_ID</tt> environment variable.
</p>
<h2 id="embedding">Embedding Images ...</h2>
<p>
After you've finished concatenating and compressing your JavaScript and
CSS files into streamlined downloads, the slowest part of your page load
is probably the images. It's common to use image sprites to avoid the
avalanche of HTTP requests that are needed to load a bunch of small images.
Unfortunately, image sprites can be complicated to position (especially
with horizontal and vertical tiling), and a real pain to create and
maintain. With a little elbow grease from Jammit, your spriting woes can be a
thing of the past.
</p>
<p>
With <b>embed_assets</b> turned on, Jammit will inline image files directly
into your compiled CSS, using
<a href="http://en.wikipedia.org/wiki/Data_URI_scheme">Data-URIs</a> in
supported browsers, and
<a href="http://en.wikipedia.org/wiki/Mhtml">MHTML</a> in Internet Explorer 7 and below.
Instead of ten CSS files referencing 30 images, you can have a single,
packaged, minified, gzipped CSS file, with the images coming in all at
once instead of piecemeal, making just a single HTTP request.
</p>
<p>
Take a look at this example (especially on a slow connection or wifi):<br>
<a href="http://jashkenas.s3.amazonaws.com/misc/jammit_example/normal.html">Normal Image Loading</a> vs.
<a href="http://jashkenas.s3.amazonaws.com/misc/jammit_example/jammit.html">Jammit Image Embedding</a><br>
</p>
<p>
Embedded images can be a little tricky, which is why using them is strictly
on an opt-in basis. After enabling <b>embed_assets</b> in the configuration file,
you'll need to whitelist the images that you'd like to make embeddable.
When processing CSS, Jammit will only embed images that have
<b>.../embed/...</b> somewhere in their path — the other images will be
left untouched. You can make a single <b>public/images/embed</b> folder for
your embedded images, or organize them into directories however you
prefer. It's not recommended to embed all of your site's images, just
the ones that conform to the following three rules:
</p>
<ol>
<li>
<b>Images that are small.</b> Large images will simply delay the rendering
of your CSS. Jammit won't embed images larger than <b>32 kilobytes</b>, because
Internet Explorer 8 won't render them.
</li>
<li>
<b>Images that are immediately visible.</b> It's better to leave the
images that are hidden at page load time to download in the background.
</li>
<li>
<b>Images that are referenced by a single CSS rule.</b> Referencing the
same embedded image in multiple rules will cause that image's contents to be
embedded more than once, defeating the purpose. Replace the duplicated
rules with an image-specific HTML class, and you're good to go.
</li>
</ol>
<p>
A final <b>cautionary note</b>. Internet Explorer's implementation of MHTML
requires the use of absolute paths in image references. This means that
the timestamp that Rails appends to the stylesheet URL (to allow
far-future expires headers) needs to also be in the contents of the
stylesheet. If a process on your webserver changes the modification time
of the cached MHTML stylesheet, it will break the image references. To fix
it, use the <tt>jammit</tt> command (with <tt>--base-url</tt>) to rebuild your assets, or simply delete
the cached file, and let Jammit automatically rebuild the file on the next
request.
</p>
<p>
If the MHTML stylesheets sound too fragile, or if you encounter any problems
with them in Internet Explorer (such as mixed-mode warnings when serving
MHTML through SSL), we recommend setting <b>embed_assets</b> to "<b>datauri</b>".
Using "<b>datauri</b>" will cause Internet Explorer 7 and below to receive
plain versions of the packaged stylesheets, while all other browsers get the
Data-URI flavor.
</p>
<h3>... and Embedding Fonts</h3>
<p>
Embedded fonts work in largely the same way as images, <b>TTF</b> and <b>OTF</b> files
that are whitelisted within an "embed" folder will be inlined as Data-URIs.
There is no MHTML variant for fonts, because Internet Explorer only supports
unembeddable <b>EOT</b> files. Embedding is especially important
for fonts in general, because it helps avoid
<a href="http://paulirish.com/2009/fighting-the-font-face-fout/">the flash of unstyled text</a>
that the browser would otherwise display while waiting for the font to
download. If you're looking to get started with web fonts,
<a href="http://www.fontsquirrel.com/fontface/generator">FontSquirrel has a great tool</a>
that can generate the proper fonts and styles you'll need. Here's an example
of a CSS rule that would activate the proper Jammit embedding:
</p>
<pre>
@font-face {
font-family: 'DroidSans';
src: url(/fonts/DroidSans.eot);
src: local('Droid Sans'), local('DroidSans'), url(/fonts/embed/DroidSans.ttf) format('truetype');
}</pre>
<h2 id="jst">JavaScript Templates</h2>
<p>
If you're using enough JavaScript to want it compressed and concatenated,
you're probably using it to generate at least a little of your
HTML. Traditionally, this has been accomplished by joining together strings
and inserting them into the DOM. A far more agreeable way to generate HTML
on the client is to use JavaScript templates (referred to here as <b>JST</b>).
</p>
<p>
Jammit helps keep your JavaScript views organized alongside your Rails
views, bundling them together into packages, and providing them pre-compiled
for your client-side code to evaluate. If left unspecified, Jammit uses a variant of
<a href="http://ejohn.org/blog/javascript-micro-templating/">John Resig's Micro Templating</a>
to compile the templates, but you can choose your preferred JavaScript templating engine
of your choosing by setting the <b>template_function</b> in <b>assets.yml</b>.
Jammit will run all of your templates through the function, and assign
each one by filename to a top-level <b>JST</b> object. For example, the following
template, <b>app/views/drivers/license.jst</b>:
</p>
<pre>
<div class="drivers-license">
<h2>Name: <%= name %></h2>
<em>Hometown: <%= birthplace %></em>
<div class="biography">
<%= bio %>
</div>
</div></pre>
<p>
Including this template within a JavaScript asset package makes it
available within the browser as the <b>JST.license</b> function.
</p>
<pre>
JST.license({name : "Moe", birthplace : "Brooklyn", bio : "Moe was always..."});</pre>
<p>
Since <b>0.5.0</b>, templates should be included in the appropriate
<tt>javascripts</tt> package. Here's an example of an <tt>assets.yml</tt>
that uses templates, and shows the location at which they'll be available
on the client. When including templates from different directories, the
common prefix is ignored, and the rest of the path becomes the name of the
template:
</p>
<pre>
javascripts:
workspace:
- app/views/accounts/badge.jst
- app/views/common/dialog.jst
- app/views/common/menu.jst</pre>
<p>
Then, from your JavaScript:
</p>
<pre>
JST['accounts/badge']
JST['common/dialog']
JST['common/menu']</pre>
<p>
To use <a href="http://documentcloud.github.com/underscore/">Underscore.js</a>
templates, set <b>template_function</b> to <tt>_.template</tt>.<br>
To use <a href="http://www.prototypejs.org/">Prototype</a> templates, set
it to <tt>new Template</tt>.<br>To use
<a href="http://github.com/janl/mustache.js">Mustache.js</a> templates,
you'll need
<a href="http://gist.github.com/234982">a little extra setup</a>.<br>
If you'd rather leave your template strings as strings, and compile them later,
set <b>template_function</b> to <tt>off</tt>.
</p>
<p>
The default extension for template files is <tt>jst</tt>,
but you can set <b>template_extension</b> in your <tt>assets.yml</tt> if you're
using an engine with a preferred extension, such as <tt>html.mustache</tt>
</p>
<h2 id="changes">Changelog</h2>
<p>
<b class="header">0.7.0</b> — <small><i>Oct 28, 2015</i></small><br>
Added Rails 4 compatibility. (It's been compatible for a while, but only if you installed from GitHub.)
Fixed Sass/SCSS compilation, but not yet compatible with the Rails development cycle since the SCSS won't be compiled to CSS in dev.
</p>
<p>
<b class="header">0.6.6</b> — <small><i>Mar 20, 2013</i></small><br>
<b>Significant internal refactor.</b>
Added ability to customize CSS compressor. Defaulted to JSMin and CSSMin.
</p>
<p>
<b class="header">0.6.5</b> — <small><i>Nov 30, 2011</i></small><br>
Added the ability to pass HTML tag options to <tt>include_javascripts</tt>.
Fixed a bug that would always cause JS to be recompiled, regardless of mtimes.
</p>
<p>
<b class="header">0.6.3</b> — <small><i>May 26, 2011</i></small><br>
Quick bugfix release for Rails 3.1 compatibility, which changes the method
signatures of <tt>javascript_include_tag</tt> and <tt>stylesheet_link_tag</tt>
in a backwards-incompatible fashion.
</p>
<p>
<b class="header">0.6.1</b> — <small><i>May 25, 2011</i></small><br>
Jammit now supports <b>UglifyJS</b> as a Java-free alternative to YUI and Closure,
for JavaScript compression.
You can now pass <tt>--packages core,embed,ui</tt> to the <tt>jammit</tt>
command, in order to only build a subset of your asset packages.
The built-in JS templating function has been upgraded to the equivalent of
the latest <tt>_.template</tt>.
Environment-specific settings are now supported in your <tt>assets.yml</tt> file.
</p>
<p>
<b class="header">0.6.0</b><br>
You can now pass <tt>debug_assets=true</tt> as a query parameter to debug
the un-packaged versions of your assets in production ... and disable this
feature by specifying <tt>allow_debugging: off</tt>.
Fixes for relative URL rewriting when Regex-unsafe characters exist in the
base path.
Fixes binary-mode file reading for some versions of Ruby 1.8 on Windows.
It's now possible to embed <tt>.woff</tt>-formatted fonts in stylesheets,
along with the rest.
</p>
<p>
<b class="header">0.5.4</b><br>
Added a <tt>Jammit.package!</tt> helper function, for use in Rake tasks.
Fixed a <tt>request_uri</tt> deprecation warning for Rails 3.
Bugfix to allow <tt>template_extension</tt> to include periods.
</p>
<p>
<b class="header">0.5.3</b><br>
You can now embed <b>WOFF</b>-formatted fonts.
Jammit warnings avoid use of <tt>Rails.logger</tt>.
Bugfixes for Ruby 1.9.2 with asset files containing Unicode characters.
</p>
<p>
<b class="header">0.5.1</b><br>
Included missing <tt>rails/routes.rb</tt> file in the Gem manifest for Rails 3.
</p>
<p>
<b class="header">0.5.0</b><br>
The Jammit gem is now compatible with Rails 3. JST template packages are
no longer specified separately. This is a backwards-incompatible change,
and you'll have to update your <tt>assets.yml</tt> file to simply include
the JST in your existing JavaScript packages, as shown above. Alongside
this change, template names are now better namespaced — see the
section on <b>JavaScript Templates</b> for the details.
Bugfix for IE8 and Data-URIs slightly under 32kb in size, as well as
for MHTML in IE7-mode in Vista.
</p>
<p>
<b class="header">0.4.4</b><br>
Jammit will now add the <tt>RAILS_ASSET_ID</tt> timestamp to image URLs
within your CSS packages, if configured, for better cache-busting.
<a href="http://github.com/ghazel/">Greg Hazel</a> contributed a series
of Jammit/Windows bug fixes.
</p>
<p>
<b class="header">0.4.3</b><br>
Bugfix for building on Windows with drive-letter absolute paths.
</p>
<p>
<b class="header">0.4.2</b><br>
Added a logged warning when you have rules in <b>assets.yml</b> that don't
match any files.
</p>
<p>
<b class="header">0.4.1</b><br>
Jammit is now able to embed <tt>@font-face</tt> web fonts in <b>TTF</b> and
<b>OTF</b> formats. The <b>embed_images</b> option has been renamed to
<b>embed_assets</b> for this change. The <b>assets.yml</b> file is now
passed through ERB before being loaded, so you can configure
environment-specific settings, just like you would with <b>database.yml</b>.
</p>
<p>
<b class="header">0.3.3</b><br>
Added <tt>css_compressor_options</tt> to assets.yml, so you can
set <tt>charset</tt> and <tt>line_break</tt> for the YUI CSS Compressor.
</p>
<p>
<b class="header">0.3.2</b><br>
If Java isn't available on your machine, Jammit will now run in a graceful
degraded mode, where assets are packaged but not compressed. You can now
pass <tt>:embed_assets => false</tt> to the <tt>include_stylesheets</tt>
helper to disable image embedding on a per-package basis.
</p>
<p>
<b class="header">0.2.8</b><br>
Jammit now correctly rewrites relative image URLs within CSS, for easier
integration with partial Rails apps deployed on sub-paths.
</p>
<p>
<b class="header">0.2.7</b><br>
The <tt>jammit</tt> command has been enhanced to check the modification times of
your packages — if no source files have changed, the package isn't
rebuilt.
</p>
<p>
<b class="header">0.2.6</b><br>
Jammit now raises an exception if Java isn't installed, or if the Java
version is unsupported by your JavaScript compressor of choice.
</p>
<p>
<b class="header">0.2.5</b><br>
When specifying your asset packages as directory globs, absolute globs are
now absolute, and relative globs are relative to RAILS_ROOT.
</p>
<p>
<b class="header">0.2.4</b><br>
Jammit now throws a <tt>ConfigurationNotFound</tt> error when attempting to load
a nonexistent configuration file. Resolved an issue with asset caching from
daemonized mongrels.
</p>
<p>
<b class="header">0.2.1</b><br>
The <tt>include_stylesheets</tt> helper now takes the same options as the
Rails <tt>stylesheet_link_tag</tt> helper (such as <tt>:media => 'print'</tt>).
</p>
<p>
<b class="header">0.2.0</b><br>
Jammit now supports the <b>Google Closure Compiler</b> as an alternative
to the YUI compressor.
</p>
<p>
<b class="header">0.1.3</b><br>
Fixed a bug that conflicted with other plugins trying to alter
ApplicationController in development.
</p>
<p>
<b class="header">0.1.1</b><br>
Added support for embedding images with stylesheet-relative paths.
Shortened the MHTML identifiers.
</p>
<p>
<b class="header">0.1.0</b><br>
Initial Jammit release.
</p>
<p>
<br>
<a href="https://www.documentcloud.org/" title="A DocumentCloud Project" style="background:none;">
<img src="http://jashkenas.s3.amazonaws.com/images/a_documentcloud_project.png" alt="A DocumentCloud Project" style="position:relative;left:-10px;">
</a>
</p>
</div>
</div>
</body>
</html>