Exclude JavaScript source maps from build

[mcsf]

The nightly build, as obtained from ​https://wordpress.org/nightly-builds/wordpress-latest.zip, currently contains .map files, source maps for 5.0's new JS packages. These aren't needed in the build and should be removed.

$ find . -name '*.map' | xargs du -hc
 28K	./wp-includes/js/dist/hooks.js.map
[32 more items...]
 16K	./wp-includes/js/dist/viewport.js.map
5.5M	total

[jorbin]

@atimmer and @omarreiss This seems like a follow up to #45145 and something we should do to reduce the zip size.

Increased zip size can be a contributing factor to updates failing, so anything we can do to keep it lower is a good thing.

[netweb]

The recent changes in #45145 that caused this are potentially going to be reverted which will resolve this issue I believe, @mcsf can you follow that ticket also and test again once those changes are reverted please.

[netweb]

@mcsf [43826] and [43824] have been reverted in [43835], could you update your local checkout when possible and test again please.

[mcsf]

confirmed that .map files are no longer present in build after running Grunt.

[ocean90]

This is related to #45156 and not #45145. The map files are still there as you can see in ​https://build.trac.wordpress.org/browser/branches/5.0/wp-includes/js/dist/.

[pento]

@ocean90: I seem to recall the map files being needed to extract translator comments. Is that correct? It looks like the comments are in the unminified JS files.

[ocean90]

@pento .map files are currently not parsed, see ​https://meta.trac.wordpress.org/browser/sites/trunk/wordpress.org/public_html/wp-content/plugins/wporg-gp-customizations/inc/cli/class-make-core-pot.php?rev=7833#L99

I'm fine with removing them if possible.

[pento]

45201.diff​ makes the build happen without the map files. Can someone please test that it doesn't have any weird side effects?

[mcsf]

Replying to pento:

45201.diff​ makes the build happen without the map files. Can someone please test that it doesn't have any weird side effects?

Nothing weird observed. I can confirm .map files are excluded.

The only exception can be found in the Twenty Nineteen directory:

$ find build -name '*.map'
build/wp-content/themes/twentynineteen/style.css.map

I've uploaded 45201.2.diff to cover this.

[pento]

Good catch, thanks @mcsf.

It's fine to keep that file in src, so I'll move that rule to not copy any .map files from src to build, instead.

[pento]

In 43931:

Build Tools: Don't include .map files in the build.

These files are fairly large, and while they're useful in development, they're not needed in the final build.

Props pento, mcsf.
See #45201.

[pento]

Turns out there was a side effect: webpack wraps the code in an eval() call when a devtool isn't specified.

[pento]

In 43932:

Build Tools: Tweak the webpack config for unminified files.

[43931] unintentionally caused the unminified files to wrap the code in an eval() call.

See #45201.

[pento]

In 43933:

Build Tools: Don't minimise CSS in the unminimised files.

See #45201.

[pento]

Okay, that reduced the nightly zip file from 18.3MB to 16.7MB. For comparison, the 4.9 nightly is 13.4MB.

I'd expect a similar size decrease in the release zip, dropping it from 13.6MB to 12MB. For comparison, the 4.9.8 release zip was 9.5MB.

I don't think there's much more space to save, the additional 3.5MB of zip is taken up by:

• Minified package JS/CSS files: 3.4MB
• Unminified package JS/CSS files: 7.5MB
• The size difference between Twenty Nineteen and Twenty Fifteen (the latter is removed from the 5.0 release zip): 700KB.

[SergeyBiryukov]

In 44282:

Build Tools: Don't include .map files in the build.

These files are fairly large, and while they're useful in development, they're not needed in the final build.

Props pento, mcsf.
Merges [43931] and [43932] to trunk.
See #45201.

[SergeyBiryukov]

In 44283:

Build Tools: Don't minimise CSS in the unminimised files.

Props pento.
Merges [43933] to trunk.
Fixes #45201.