Prefix every CSS selector with a custom namespace
.a => .prefix .a
$ npm install postcss-prefix-selector
const prefixer = require('postcss-prefix-selector')
// css to be processed
const css = fs.readFileSync("input.css", "utf8")
const out = postcss().use(prefixer({
prefix: '.some-selector',
exclude: ['.c'],
// Optional transform callback for case-by-case overrides
transform: function (prefix, selector, prefixedSelector, filePath, rule) {
if (selector === 'body') {
return 'body' + prefix;
} else {
return prefixedSelector;
}
}
})).process(css).css
Using the options above and the CSS below...
body {
background: red;
}
.a, .b {
color: aqua;
}
.c {
color: coral;
}
You will get the following output
body.some-selector {
background: red;
}
.some-selector .a, .some-selector .b {
color: aqua;
}
.c {
color: coral;
}
Use it like you'd use any other PostCSS plugin. If you also have autoprefixer
in your webpack config then make sure that postcss-prefix-selector
is called first. This is needed to avoid running the prefixer twice on both standard selectors and vendor specific ones (ex: @keyframes
and @webkit-keyframes
).
module: {
rules: [{
test: /\.css$/,
use: [
require.resolve('style-loader'),
require.resolve('css-loader'),
{
loader: require.resolve('postcss-loader'),
options: {
postcssOptions: {
plugins: {
"postcss-prefix-selector": {
prefix: '.my-prefix',
transform(prefix, selector, prefixedSelector, filePath, rule) {
if (selector.match(/^(html|body)/)) {
return selector.replace(/^([^\s]*)/, `$1 ${prefix}`);
}
if (filePath.match(/node_modules/)) {
return selector; // Do not prefix styles imported from node_modules
}
const annotation = rule.prev();
if (annotation?.type === 'comment' && annotation.text.trim() === 'no-prefix') {
return selector; // Do not prefix style rules that are preceded by: /* no-prefix */
}
return prefixedSelector;
},
},
autoprefixer: {
browsers: ['last 4 versions']
}
}
}
}
}
]
}]
}
Following the same way of Webpack but for Vite:
import prefixer from 'postcss-prefix-selector';
import autoprefixer from 'autoprefixer';
...
export default defineConfig({
...
css: {
postcss: {
plugins: [
prefixer({
prefix: '.my-prefix',
transform(prefix, selector, prefixedSelector, filePath, rule) {
if (selector.match(/^(html|body)/)) {
return selector.replace(/^([^\s]*)/, `$1 ${prefix}`);
}
if (filePath.match(/node_modules/)) {
return selector; // Do not prefix styles imported from node_modules
}
const annotation = rule.prev();
if (annotation?.type === 'comment' && annotation.text.trim() === 'no-prefix') {
return selector; // Do not prefix style rules that are preceded by: /* no-prefix */
}
return prefixedSelector;
},
}),
autoprefixer({}) // add options if needed
],
}
},
...
});
Name | Type | Description |
---|---|---|
prefix |
string |
This string is added before every CSS selector |
exclude |
string[] or RegExp[]
|
It's possible to avoid prefixing some selectors by passing an array of selectors |
transform |
Function |
In cases where you may want to use the prefix differently for different selectors, it is possible to pass in a custom transform method |
ignoreFiles |
string[] or RegExp[]
|
List of ignored files for processing |
includeFiles |
string[] or RegExp[]
|
List of included files for processing |
This project was originally created by @jongleberry and is being maintained by @RadValentin. If you have any questions, feel free to ping the latter.
Please contribute! If you have any questions or bugs, open an issue. Or, open a pull request with a fix.
This project uses Mocha. If you submit a PR, please add appropriate tests and make sure that everything is green for your branch.
MIT © 2015-2022 Jonathan Ong.