![Bjørn Erik Pedersen](/assets/img/avatar_default.png)
cb18a5183 Fix broken link 07a0198bf Config: Place Google Analytics tag ID under the services key 4bf0c719f Fix typo 50d8ad1af Fix muiltilingual menu definition instructions 1a32519a9 Fix typos 6f34ca8e0 Explain usage of front matter to target a template 5bd977257 Improve goldmark config docs 447632938 Remove Docker notes from installation instructions 84741d173 Update reference to hugo.work 0338d7c71 Fix menu template f5d2f5ed4 Fix typos in content/en/functions/fmt a3a40ff99 Add return type to functions 85ac3e779 Remove outdated feature image d47d889e4 Fix signatures 7551ba28f Document safe.JSStr function e77993be0 Document keyVals function 4dba20db3 Update theme babf91544 Update echoparam 8c8203efa Adjust related functions 4cb1b30fc Fix example ba95eca64 Improve showcase prose 5d3dcf366 Add Overmind Studios showcase 8d634ac70 Change code blocks from indented to fenced cfab978e6 Add missing code fences 407dd5c47 Limit related pages for functions to other functions 9fa67d981 Fix .Site.LastChange doc 393aa16d0 netlify: Hugo 0.119.0 f864af97a docs: Even more about images.Process 9d772d5f0 docs: More about images.Process bc655f869 docs: Regen docshelper 41c3536d1 Merge commit '9aec42c5452b3eb224888c50ba1c3f3b68a447e9' 918ed53f4 Add images.Process filter 573645883 Add $image.Process a1151b0fd Add images.Opacity filter git-subtree-dir: docs git-subtree-split: cb18a5183fc62f301ffde50b8c39f03e4b897aec
4.1 KiB
Executable file
title | description | categories | keywords | menu | weight | signatures | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PostProcess | Allows delaying of resource transformations to after the build. |
|
|
50 |
|
Usage
Marking a resource with resources.PostProcess
delays any transformations to after the build, typically because one or more of the steps in the transformation chain depends on the result of the build (e.g. files in public
).
A prime use case for this is CSS purging with PostCSS.
There are currently two limitations to this:
-
This only works in
*.html
templates (i.e. templates that produces HTML files). -
You cannot manipulate the values returned from the resource's methods. E.g. the
upper
in this example will not work as expected:{{ $css := resources.Get "css/main.css" }} {{ $css = $css | resources.PostCSS | minify | fingerprint | resources.PostProcess }} {{ $css.RelPermalink | upper }}
CSS purging with PostCSS
{{% note %}}
There are several ways to set up CSS purging with PostCSS in Hugo. If you have a simple project, you should consider going the simpler route and drop the use of resources.PostProcess
and just extract keywords from the templates. See the Tailwind documentation for some examples.
{{% /note %}}
The below configuration will write a hugo_stats.json
file to the project root as part of the build. If you're only using this for the production build, you should consider placing it below config/production.
{{< code-toggle file="hugo" >}} [build.buildStats] enable = true {{< /code-toggle >}}
See the configure build documentation for details and options.
postcss.config.js
const purgecss = require('@fullhuman/postcss-purgecss')({
content: [ './hugo_stats.json' ],
defaultExtractor: (content) => {
let els = JSON.parse(content).htmlElements;
return els.tags.concat(els.classes, els.ids);
}
});
module.exports = {
plugins: [
...(process.env.HUGO_ENVIRONMENT === 'production' ? [ purgecss ] : [])
]
};
Note that in the example above, the "CSS purge step" will only be applied to the production build. This means that you need to do something like this in your head template to build and include your CSS:
{{ $css := resources.Get "css/main.css" }}
{{ $css = $css | resources.PostCSS }}
{{ if hugo.IsProduction }}
{{ $css = $css | minify | fingerprint | resources.PostProcess }}
{{ end }}
<link href="{{ $css.RelPermalink }}" rel="stylesheet" />
Hugo environment variables available in PostCSS
These are the environment variables Hugo passes down to PostCSS (and Babel), which allows you do do process.env.HUGO_ENVIRONMENT === 'production' ? [autoprefixer] : []
and similar:
- PWD
- The absolute path to the project working directory.
- HUGO_ENVIRONMENT
- The value e.g. set with
hugo -e production
(defaults toproduction
forhugo
anddevelopment
forhugo server
). - HUGO_PUBLISHDIR
- {{< new-in "0.109.0" >}} The absolute path to the publish directory (the
public
directory). Note that the value will always point to a directory on disk even when runninghugo server
in memory mode. If you write to this folder from PostCSS when running the server, you could run the server with one of these flags:
hugo server --renderToDisk
hugo server --renderStaticToDisk
Also, Hugo will add environment variables for all files mounted below assets/_jsconfig
. A default mount will be set up with files in the project root matching this regexp: (babel|postcss|tailwind)\.config\.js
.
These will get environment variables named on the form HUGO_FILE_:filename:
where :filename:
is all upper case with periods replaced with underscore. This allows you to do this and similar:
let tailwindConfig = process.env.HUGO_FILE_TAILWIND_CONFIG_JS || './tailwind.config.js';