For those of you who didn't see bug 26791, our use of JSMin has been
found to conflict with our GPL license. After assessing other options (
https://bugzilla.wikimedia.org/show_bug.cgi?id=26791#c8 ) Roan and I
decided to try and use the minification from JavaScriptPacker, but not
its overly clever but generally useless packing techniques. The result
is a minifier that outperforms our current minifier in both how quickly
it can minify data and how small the minified output is.
JavaScriptDistiller, as I sort of randomly named it, minifies JavaScript
code at about 2x the speed of Tim's optimized version of JSMin, and 4x
the speed of the next fastest PHP port of JSMin (which is generally
considered the standard distribution).
Similar to Tim's modified version of JSMin, we chose to retain vertical
whitespace by default. However we chose not to retain multiple
consecutive empty new lines, which are primarily seen where a large
comment block has been removed. We feel there is merit to the argument
that appx. 1% bloat is a reasonable price to pay for making it easier to
read production code, since leaving each statement on a line by itself
improves readability and users will be more likely to be able to report
problems that are actionable. We do not however find the preservation of
line numbers of any value, since in production mode most requests are
for many modules which are concatenated, making line numbers for most of
the code useless anyways.
This is a breakdown based on "ext.vector.simpleSearch"
* 3217 bytes (1300 compressed)
* 2178 bytes (944) after running it through the version of JSMin that
was in our repository. Tim modified JSMin to be faster and preserve line
numbers by leaving behind all vertical whitespace.
* 2160 bytes (938 compressed) after running it through
JavaScriptDistiller, which applies aggressive horizontal minification
plus collapsing multiple consecutive new lines into a single new line.
* 2077 bytes (923 compressed) after running it through
JavaScriptDistiller with the vertical space option set to true, which
applies aggressive horizontal minification as well as some basic
vertical minification. This option is activated through
$wgResourceLoaderMinifyJSVerticalSpace, which is false by default.
The code was committed in r80656.
- Trevor (and Roan)