[wp-hackers] Packing JavaScript

Computer Guru computerguru at neosmart.net
Tue Sep 18 12:11:21 GMT 2007

The best JS-compresser I've seen (in terms of compatiblity and size) is from
the DoJo toolkit:

Just my 2 cents..

On 9/18/07, Alex Günsche <ag.ml2007 at zirona.com> wrote:
> Hi all,
> WordPress comes with tons of JavaScript by default. Regardless of any
> server-based compression, it's always a big bunch of bytes to download.
> Ok, most of it is in the admin backend, but still, I think there's a
> possiliblity for optimizazion -- especially if you think of WPMU
> communities.
> Some of you might know the nice JS packer by Dean Edwards [1], e.g. used
> by MooTools [2] by default. It is a very clever tool to "compress"
> JavaScript files to 30-70 percent of the original size.
> I have made some tests on my WordPress installs, one is WP 2.0.11, the
> other is 2.3-beta3.
> With a little shell foo, you'll find out the amount of JS code in the WP
> core:
> sum=0; for j in $(for i in $(find ./wp-admin/ ./wp-includes/ -iname
> "*\.js"); do du -b $i | cut -f 1; done); do sum=$[ $sum+$j ]; done; echo
> $sum
> The outcome is: 357642 bytes for WP 2.0.11 and 1020175 bytes (!) for WP
> 2.3-beta3.
> Now I've taken the php5 version of the packer [3] to test it on the JS
> files in the WP core. I extracted the package to WP_ROOT/jspacker/ and
> uncommented the argv section in example-file.php. Then I ran the
> following:
> for i in $(find ./wp-admin/ ./wp-includes/ -iname "*\.js" | sed
> 's|\.js$||'); do cp $i.js $i.src.js; php ./jspacker/example-file.php$i.src.js $i.js; done
> Running the first command line again (the sum stuff) and subtracting the
> results from the respective previous results (because it also counts the
> new/copied src files) shows that the compressed JS files now make a
> total of 195703 bytes (2.0.11) and 562329 bytes (2.3-beta3). This is
> about 50% of the total size saved.
> Now the big question is: Does it break the JS? It is to say, that in
> rare cases, the packer can break JS code. And indeed, some short tests
> on both versions showed the following:
> - Most JS, including the remote stuff, works as expected.
> - On 2.0.11, TinyMCE seemed not to be able to initialize, so WP came
> with the fallback editor, though that one worked.
> - On 2.3-beta3, TinyMCE works fine, though switching between Visual and
> Code doesn't work.
> In Firefox, the web developer toolbar shows some errors with the syntax
> in the packed files, which explain the above problems.
> Bottomline so far: There is a possibility for much optimization in the
> size of JS downloads. There are some minor problems, which can be solved
> though (e.g.: fix files manually, not compress files that seem to break,
> fix packer).
> Now one can even imagine to go one step further: I find it also annoying
> that one has to download so many files. In theory, it would be better to
> pack all JS into *one* big file and let the UA download that one. This
> would significantly reduce the number of HTTP requests.
> Of course, I wouldn't want to merge TinyMCE, Prototype and all the other
> JS in one file in the source distribution, but one could imagine having
> a backend JS handler that gathers all JS files to be inserted and
> delivers them as one. We do have API hooks for JS (at least in the
> admin), so it wouldn't be too hard to gather the files.
> It's even possible to imagine a global on-the-fly packer combined with a
> JS cache, which could again bring additional performance.
> Just some ideas ... what do you guys think?
> Kind regards,
> Alex
> [1] http://dean.edwards.name/packer/
> [2] http://mootools.net/download
> [3] http://joliclic.free.fr/php/javascript-packer/en/
> --
> Alex Günsche, Zirona OpenSource-Consulting
> Blogs: http://www.zirona.com/ | http://www.regularimpressions.net
> PubKey for this address: http://www.zirona.com/misc/ag.ml2007.asc
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Computer Guru
NeoSmart Technologies

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