css-selector-extract


With selector extracting, it is possible to extract certain CSS selectors (RegEx can be used to match selectors) from CSS code. This is especially useful if you want to extract only a few CSS classes from a huge library or framework.

Demos

``js
const cssSelectorExtract = require('css-selector-extract');

const options = {
// CSS source code as string.
css: '.btn { } .btn-alert { } .btn-success { }',
// Array of selectors which should get extracted.
filters: ['.btn']
};

// Asynchronous:
cssSelectorExtract.process(options).then((extractedCss) => {
console.log(extractedCss); // Outputs: .btn { }.
});

// Synchronous:
const extractedCss = cssSelectorExtract.processSync(options);
console.log(extractedCss); // Outputs: .btn { }.
`

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`js
const cssSelectorExtract = require('css-selector-extract');

const options = {
// CSS source code as string.
css: '.btn { } .btn-alert { } .btn-success { }',
// Array of selector filter objects with selectors
// which should get extracted and replaced.
filters: [{ selector: '.btn', replacement: '.button' }]
};

// Asynchronous:
cssSelectorExtract.process(options).then((extractedCss) => {
console.log(extractedCss); // Outputs: .button { }.
});
`

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#### Filter selectors

`js
const cssSelectorExtract = require('css-selector-extract');

const options = {
css: '.btn { } .btn-alert { }',
filters: [/^\..+-alert/]
};

cssSelectorExtract.process(options).then((extractedCss) => {
console.log(extractedCss); // Outputs: .btn-alert { }.
});
`

#### Replace selectors

`js
const cssSelectorExtract = require('css-selector-extract');

const options = {
css: '.btn { } .btn-alert { }',
filters: [{ selector: /^\.btn(.*)/, replacement: '.button$1' }]
};

cssSelectorExtract.process(options).then((extractedCss) => {
console.log(extractedCss); // Outputs: .button { } .button-alert { }.
});
`

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Install the corresponding postcss syntax plugin (e.g. postcss-scss or postcss-less).

`js
const cssSelectorExtract = require('css-selector-extract');
const postcssScss = require('postcss-scss');

const options = {
css: '.nested { .selector { } }',
filters: ['.nested'],
postcssSyntax: postcssScss
};

cssSelectorExtract.process(options).then((extractedCss) => {
console.log(extractedCss);
});
`

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Usually css-selector-extract removes all nodes which do not match the given selectors. However under some circumstances it might be useful to preserve the original line numbers (e.g. to keep source map references intact).

`js
const cssSelectorExtract = require('css-selector-extract');

const options = {
css: '.multiple { } .selectors {}',
filters: ['.some-selector'],
preserveLines: true
};

cssSelectorExtract.process(options).then((extractedCss) => {
// Outputs the extracted selector(s) with empty lines where
// other selectors got removed to preserve line numbers.
console.log(extractedCss);
});
`

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`js
import { process, processSync } from 'css-selector-extract';

const options = {
// CSS source code as string.
css: '.btn { } .btn-alert { } .btn-success { }',
// Array of selectors which should get extracted.
filters: ['.btn']
};

// Asynchronous:
process(options).then((extractedCss) => {
console.log(extractedCss); // Outputs: .btn { }.
});

// Synchronous:
const extractedCss = processSync(options);
console.log(extractedCss); // Outputs: .btn { }.
`

Upgrade from 2.x.x to 3.x.x

With version 3.0.0 css-selector-extract takes an object as it's only parameter.

`js
const cssSelectorExtract = require('css-selector-extract');
const postcssScss = require('postcss-scss');

// New way:
const options = {
css: '.btn { } .btn-alert { } .btn-success { }',
filters: ['.btn'],
postcssSyntax: postcssScss
};
cssSelectorExtract.process(options);
cssSelectorExtract.processSync(options);

// Old way:
const css = '.btn { } .btn-alert { } .btn-success { }';
const selectorFilters = ['.btn'];
cssSelectorExtract.process(css, selectorFilters, postcssScss);
cssSelectorExtract.processSync(css, selectorFilters, postcssScss);
`

Development

See CONTRIBUTING.md

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`bash
npm test
``

About

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Markus Oberlehner
Website: https://markus.oberlehner.net
Twitter: https://twitter.com/MaOberlehner
PayPal.me: https://paypal.me/maoberlehner
Patreon: https://www.patreon.com/maoberlehner

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MIT