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1214f6ffb Document cleanDestinationDir configuration setting 27ca65463 Clarify .Page.Param method (#1953) 3fa1792d2 Document the usage of `hardWrap` option for markdown rendering (#1951) 8b5afdfb4 Update theme 207e7f0a0 fix docs for getting remote font 1f7094b9e Correct typo f9d6445c4 Added missing `/` in URL generator (#1946) 3a22ee7d6 Remove translations b3b900f3f Update introduction.md aca440052 rm Forestry - facing end-of-life shortly (#1944) af0014e14 Update scss-sass.md 1c43bbbc9 Merge branch 'docs/goworkspace' d034175ca netlify: Hugo 0.109.0 d3a6a5c3f Merge branch 'tempv0.109.0' e033dbead docs: Regen docs helper JSON 452bf675c resource/page: Add Page.Ancestors 12edd7363 Add some docs for workspaces 8f0fcba6b Add HUGO_PUBLISHDIR to the Node environment 4e66d98ad Update theme 808aee6f6 config: Update to ga v4 1de2bc5a9 config: Update to ga v4 ddb5fd6b0 Merge commit '41bc6f702aa54200530efbf4267e5c823df3028d' 54c54bf76 modules: Adjust watch logic vs workspace use definitions git-subtree-dir: docs git-subtree-split: 1214f6ffbf680e853746aaeb6cb097b28c0c556b
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title | description | date | categories | keywords | menu | weight | sections_weight | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PostProcess | Allows delaying of resource transformations to after the build. | 2020-04-09 |
|
|
39 | 39 |
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="config" >}} [build] writeStats = true {{< /code-toggle >}}
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 (and the alias HUGO_ENV)
- 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 do do this and similar:
let tailwindConfig = process.env.HUGO_FILE_TAILWIND_CONFIG_JS || './tailwind.config.js';