@localnerve/sass-asset-functions
v6.2.0
Published
compass-style asset functions for dart-sass or other sass compilers
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Sass Asset Functions
Supplies a set of functions to Sass that keep physical asset location details out of your source code. Also allows one to define a cache-busting policy or specify asset hosts by url.
This module supplies functions to a Sass compiler which can be called from your Sass code.
For example, the image-url
used here in place of url
adds build-time configuration to resolve the file to the proper location as seen from the web:
.some-selector {
background-image: image-url('cat.jpg');
}
NB Please note that the functions
option of dart-sass/node-sass is still experimental (>= v3.0.0).
Origin
This module provides some of the asset functions that came with Compass. Originally a fork of node-sass-asset-functions that was never merged.
Release Notes
Functions Exposed to Sass
image-url($filename: null, $only_path: false)
image-width($filename: null)
image-height($filename: null)
font-url($filename: null, $only-path: false)
font-files($filenames...)
inline-image($filename: null, $mime-type: null)
Usage
Basic usage is as easy as setting the functions
property:
// non-module, require usage
const sass = require('sass');
const { default: assetFunctions } = require('@localnerve/sass-asset-functions');
const result = sass.compile(scss_filename, {
functions: assetFunctions(/* options */)
[, options...]
});
// module usage
import sass from 'sass';
import assetFunctions from '@localnerve/sass-asset-functions';
const result = sass.compile(scss_filename, {
functions: assetFunctions(/* options */)
[, options...]
});
Options
All options are optional.
| name | type | description |
| --- | --- | --- |
| sass
| Object | A reference to an alternate Sass compiler to use other than dart-sass (must expose types
). Defaults to undefined
and a dart-sass reference is used |
| legacyAPI
| Boolean | truthy to use the legacy sass API via the sass render
function. Defaults to false
|
| async
| Boolean | truthy to use modern sass API via the compileAsync
function. Required if supplied asset_cache_buster
or asset_host
function options are asynchronous. Defaults to false
|
| images_path
| String | The build-time file path to images. Defaults to public/images
|
| fonts_path
| String | The build-time file path to fonts. Defaults to public/fonts
|
| http_images_path
| String | The path to images as seen from the web (nothing to do with http). Defaults to /images
|
| http_fonts_path
| String | The path to images as seen from the web (nothing to do with http). Defaults to /fonts
|
| asset_cache_buster
| Function | Signature (http_path, real_path, callback(new_url)). Supply to perform url transform for image-url
or font-url
, presumably for asset cache busting, but useful for any change to the url path (before fragment) |
| asset_host
| Function | Signature (http_path, callback(new_url)). Supply to perform url transform for image-url
or font-url
, presumably to define an asset host, but useful for any change to the url before the path |
Examples
You can specify the paths to your resources using the following options (shown with defaults):
{
images_path: 'public/images', // local directory
fonts_path: 'public/fonts',
http_images_path: '/images', // web path
http_fonts_path: '/fonts'
}
So if your project images reside in public/img
at build-time instead of public/images
, you use it as follows:
const sass = require('sass');
const { default: assetFunctions } = require('@localnerve/sass-asset-functions');
const result = sass.compile(scss_filename, {
functions: assetFunctions({
images_path: 'public/img',
http_images_path: '/images'
})
[, options...]
});
sass
: Overriding the default compiler with Node-Sass
Example using the node-sass compiler using the new option sass
.
const sass = require('node-sass');
const { default: assetFunctions } = require('@localnerve/sass-asset-functions');
const result = sass.compile(scss_filename, {
functions: assetFunctions({ sass })
[, options...]
});
asset_host
: a function which completes with a string used as asset host.
const result = sass.compile(scss_filename, {
functions: assetFunctions({
asset_host: (http_path, done) => {
done('http://assets.example.com');
// or use the supplied path to calculate a host
done(`http://assets${http_path.length % 4}.example.com`);
}
})
[, options...]
});
asset_cache_buster
: a function to rewrite the asset path
When this function returns a string, it's set as the query of the path. When returned an object, path
and query
will be used.
const result = sass.compile(scss_filename, {
functions: assetFunctions({
asset_cache_buster: (http_path, real_path, done) => {
done('v=123');
}
})
[, options...]
});
A more advanced example:
Here we include the file's hexdigest in the path, using the hexdigest
module.
For example, /images/myimage.png
would become /images/myimage-8557f1c9b01dd6fd138ba203e6a953df6a222af3.png
.
const sass = require('sass');
const path = require('path');
const fs = require('fs');
const hexdigest = require('hexdigest');
const { default: assetFunctions } = require('@localnerve/sass-asset-functions');
const result = sass.compileAsync(scss_filename, {
functions: assetFunctions({
async: true,
asset_cache_buster: (http_path, real_path, done) => {
hexdigest(real_path, 'sha1', (err, digest) => {
if (err) {
// an error occurred, maybe the file doesn't exist.
// Calling `done` without arguments will result in an unmodified path.
done();
} else {
const extname = path.extname(http_path);
const basename = path.basename(http_path, extname);
const new_name = `${basename}-${digest}${extname}`;
done({path: path.join(path.dirname(http_path), new_name), query: null});
}
});
}
})
[, options...]
});
Contributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create new Pull Request