postcss-remove-classes/src/index.js

PostCSS plugin to remove specific classes from a CSS file

/* eslint no-use-before-define: [0], no-case-declarations: [0], no-param-reassign: [0] */

import { curry, includes, reject, trim } from 'lodash/fp';
import parser from 'postcss-selector-parser';

export const classNameMatches = curry((matchArg, className) => {
  if (Array.isArray(matchArg)) {
    return includes(className, matchArg);
  } else if (matchArg instanceof RegExp) {
    return matchArg.test(className);
  }
  return matchArg === className;
});

const nodesAreEmpty = node => node.nodes.length === 0;

export const removeClasses = (matchesClassName, selector) => {
  const parseNode = (node) => {
    switch (node.type) {
      case 'root':
        node.nodes = reject(parseNode, node.nodes);
        return false;
      case 'selector':
        const didRemoveNodes = node.nodes.some(parseNode);
        if (didRemoveNodes) {
          node.empty();
        }
        return didRemoveNodes;
      case 'class':
        const shouldRemoveNode = matchesClassName(node.value);
        return shouldRemoveNode;
      case 'pseudo':
        node.nodes = reject(parseNode, node.nodes);

        const argumentsIsEmpty = nodesAreEmpty(node);
        if (node.value === ':matches' || node.value === ':has') {
          return argumentsIsEmpty;
        } else if (node.value === ':not' && argumentsIsEmpty) {
          node.remove();
        }
        return false;
      case 'attribute':
      case 'combinator':
      case 'comment':
      case 'id':
      case 'nesting':
      case 'string':
      case 'tag':
      case 'universal':
        return false;
      default:
        throw new Error(`Unhandled type: ${node.type}`);
    }
  };

  const ast = parser(parseNode).processSync(selector);

  return trim(String(ast));
};

export default matchArg => ({
  postcssPlugin: 'remove-classes',
  prepare() {
    const matches = classNameMatches(matchArg);

    return {
      Rule(rule) {
        const newSelector = removeClasses(matches, rule.selector);
        if (!newSelector) {
          rule.remove();
        } else if (newSelector !== rule.selector) {
          rule.selector = newSelector;
        }
      },
    };
  },
});