Css-node-extract NPM

css-node-extract

Extract certain nodes from CSS code.

Filters

at-rules: @media, @supports, @mixin,...
declarations: $variable, @variable,...
functions: @function
mixins: @mixin and .less-mixin-selector()
rules: .class-selector, #id-selector,...
silent: Extract only nodes that do not compile to CSS code (mixins, placeholder selectors, variables,...)
variables: $sass-variable and @less-variable
make-your-own: Define custom filters

Demos

const cssNodeExtract = require('css-node-extract');
const postcssScssSyntax = require('postcss-scss');

const options = {
  // CSS source code as string.
  css: '$variable: "value"; .selector { } .other-selector { }',
  // Extract only variables.
  filters: ['variables'],
  // postcss syntax plugin to add support for SCSS code.
  postcssSyntax: postcssScssSyntax
};

// Asynchronous:
cssNodeExtract.process(options).then((extractedCss) => {
  console.log(extractedCss); // Outputs: '$variable: "value";'.
});

// Synchronous:
const extractedCss = cssNodeExtract.processSync(options);
console.log(extractedCss); // Outputs: '$variable: "value";'.

Custom filter

const cssNodeExtract = require('css-node-extract');

const options = {
  // CSS source code as string.
  css: '@keyframes { } .selector { } .other-selector { }',
  filters: ['my-keyframe-filter'],
  customFilters: {
    myKeyframeFilter: [
      [
        { property: 'type', value: 'atrule' },
        { property: 'name', value: 'keyframes' }
      ]
    ]
  }
};

cssNodeExtract.process(options).then((extractedCss) => {
  console.log(extractedCss); // Outputs: '@keyframes { }'.
});

Preserve lines

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

const cssNodeExtract = require('css-node-extract');

const options = {
  css: '$variable: "value"; .selector { } .other-selector { }',
  filters: ['variables'],
  postcssSyntax: postcssScssSyntax,
  preserveLines: true
};

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

ES2015 named exports

import { process, processSync } from 'css-node-extract';
import postcssScssSyntax from 'postcss-scss';

const options = {
  // CSS source code as string.
  css: '$variable: "value"; .selector { } .other-selector { }',
  // Extract only variables.
  filters: ['variables'],
  // postcss syntax plugin to add support for SCSS code.
  postcssSyntax: postcssScssSyntax
};

// Asynchronous:
process(options).then((extractedCss) => {
  console.log(extractedCss); // Outputs: '$variable: "value";'.
});

// Synchronous:
processSync(options);
console.log(extractedCss); // Outputs: '$variable: "value";'.

Upgrade from 1.x.x to 2.x.x

With version 2.0.0 the handling of custom filters was changed. The customFilter option was renamed to customFilters and this option now takes an object instead of an array. Instead of defining one custom filter named custom, you can now define unlimited custom filters with custom names.

Upgrade from 0.x.x to 1.x.x

With version 1.0.0 the filterNames option was renamed to filters.

// New
const options = {
  css: '$variable: "value"; .selector { } .other-selector { }',
  filters: ['variables'],
  postcssSyntax: postcssScssSyntax
};

// Old
const options = {
  css: '$variable: "value"; .selector { } .other-selector { }',
  filterNames: ['variables'],
  postcssSyntax: postcssScssSyntax
};