Javascript compression / How to hook in to rails development

Hi there,

I thought it’s rather neat to use the javascript compression from

http://dojotoolkit.org/docs/compressor_system.html

This removes javascript comments and renames variables and seems pretty
reliable and effective.

For example, I keep the original htmlarea.js file from
http://xinha.gogo.co.nz/
in a file htmlarea.js.txt and it compresses from 200K to 100K. With
gzip it compresses further down to 27K as opposed to 50K without the
intermediate custom_rhino compression (hopefully I can make use of
Apache 2.0 mod_deflate soon.)

So I set up a Rake task for all my javascript files

FILE lib/tasks/compress_javascript.rake

task :javascript do
{
‘public/stb.js’ => 0,
‘public/tabs.js’ => 23,
‘public/xinha/htmlarea.js’ => 33,
‘public/javascripts/prototype.js’ => 11,
‘public/javascripts/controls.js’ => 21,
‘public/javascripts/effects.js’ => 23,
‘public/calendar-dateparse.js’ => 19,
}.each do |filename, copyrightlength|
to_compress = filename + ‘.txt’
compress_out = filename
unless uptodate?(compress_out, to_compress)
puts to_compress.to_s + " -> " + compress_out
if copyrightlength>0
%x{ echo “// Adapted for stephansmap.org and compressed
with custom_rhino from #{to_compress.gsub(/public/,’’)}” >
#{compress_out}; head -#{copyrightleng
th} #{ to_compress } >> #{compress_out}};
else
%x{ echo ‘’ > #{ compress_out } }
end
%x{ java -jar extra/custom_rhino.jar -c #{ to_compress }

#{ compress_out } 2>&1 }

       end
     end

end

END FILE

Now, how can I have this task executed during development? When I change
one of the js.txt files and refresh a page, it would be nice to have
this compression executed so I am looking at the site based on new
javascript code the same way I can change controller ruby code and the
changes are reflected on each access.

Stephan

Mohit wrote:

Sorry, this doesn’t relate to your question, but it’s worth pointing out
that if people are using JS code created by others, they should be aware
of ‘license’ concerns. Many JS coders (as others) require that the
license and acknowledgments remain in the Javascript file. It’s worth
remembering that when using tools that strip comments :slight_smile:

Cheers,
Mohit.

I addressed the license issues in the rake task, see the condition

if copyrightlength>0
%x{ echo “// Adapted for stephansmap.org and compressed
with custom_rhino from #{to_compress.gsub(/public/,’’)}” >
#{compress_out}; head -#{copyrightlength} #{ to_compress } >>
#{compress_out}};

The “head …” instruction puts the original copyright notice at the top
of the compressed file. I counted manually to see how many lines to copy
over. Plus the top of the compressed file says how to obtain a copy of
the file with my modifications ( append .txt to the filename )

I think that way the copyrights and licenses are respected!

Stephan

Stephan wrote:

Hi there,

I thought it’s rather neat to use the javascript compression from

http://dojotoolkit.org/docs/compressor_system.html

This removes javascript comments and renames variables and seems pretty
reliable and effective.

For example, I keep the original htmlarea.js file from
http://xinha.gogo.co.nz/
in a file htmlarea.js.txt and it compresses from 200K to 100K. With
gzip it compresses further down to 27K as opposed to 50K without the
intermediate custom_rhino compression (hopefully I can make use of
Apache 2.0 mod_deflate soon.)

So I set up a Rake task for all my javascript files

FILE lib/tasks/compress_javascript.rake

task :javascript do
{
‘public/stb.js’ => 0,
‘public/tabs.js’ => 23,
‘public/xinha/htmlarea.js’ => 33,
‘public/javascripts/prototype.js’ => 11,
‘public/javascripts/controls.js’ => 21,
‘public/javascripts/effects.js’ => 23,
‘public/calendar-dateparse.js’ => 19,
}.each do |filename, copyrightlength|
to_compress = filename + ‘.txt’
compress_out = filename
unless uptodate?(compress_out, to_compress)
puts to_compress.to_s + " -> " + compress_out
if copyrightlength>0
%x{ echo “// Adapted for stephansmap.org and compressed
with custom_rhino from #{to_compress.gsub(/public/,’’)}” >
#{compress_out}; head -#{copyrightleng
th} #{ to_compress } >> #{compress_out}};
else
%x{ echo ‘’ > #{ compress_out } }
end
%x{ java -jar extra/custom_rhino.jar -c #{ to_compress }

#{ compress_out } 2>&1 }

       end
     end

end

END FILE

Now, how can I have this task executed during development? When I change
one of the js.txt files and refresh a page, it would be nice to have
this compression executed so I am looking at the site based on new
javascript code the same way I can change controller ruby code and the
changes are reflected on each access.

Stephan

Stephan W. wrote:

http://xinha.gogo.co.nz/
{
unless uptodate?(compress_out, to_compress)

one of the js.txt files and refresh a page, it would be nice to have
this compression executed so I am looking at the site based on new
javascript code the same way I can change controller ruby code and the
changes are reflected on each access.

Stephan

Sorry, this doesn’t relate to your question, but it’s worth pointing out
that if people are using JS code created by others, they should be aware
of ‘license’ concerns. Many JS coders (as others) require that the
license and acknowledgments remain in the Javascript file. It’s worth
remembering that when using tools that strip comments :slight_smile:

Cheers,
Mohit.

Stephan W. wrote:

Cheers,

Excellent!!
Cheers,
mohit.

On Sunday 13 August 2006 20:02, Mohit S. wrote:

Stephan W. wrote:

Hi there,

I thought it’s rather neat to use the javascript compression from

http://dojotoolkit.org/docs/compressor_system.html
[snip]

Sorry, this doesn’t relate to your question, but it’s worth pointing
out that if people are using JS code created by others, they should
be aware of ‘license’ concerns. Many JS coders (as others) require
that the license and acknowledgments remain in the Javascript file.
It’s worth remembering that when using tools that strip comments :slight_smile:

I’m not really sure if this applies to compressed versions of a file,
possibly bundled in a single file with other code. I tend to view this
the same as the relationship between plain text source code and
compiled binary code. While a programmer expects their
copyright/license notice to be retained in the source code, in the
binary it has vanished. Of course, combined and compressed JavaScript
is not binary code, but it involves an inordinate amount of work to
extract the original pieces in a fashion that they are individually
recognizable and reusable.

If you want to be super prudent, include all the licenses at the top of
the compressed JavaScript code. For my taste it would be good enough –
and required – to include them in the license notice of the enclosing
package.

Michael


Michael S.
mailto:[email protected]
http://www.schuerig.de/michael/

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