PostCSS Custom Selectors

// dependencies
var fs = require('fs')
var postcss = require('postcss')
var selector = require('postcss-custom-selectors')

// css to be processed
var css = fs.readFileSync('input.css', 'utf8')

// process css using postcss-custom-selectors
var output = postcss()
  .use(selector())
  .process(css)
  .css

console.log('\n====>Output CSS:\n', output)  

var output = postcss(selector())
  .process(css)
  .css

var options = {
  lineBreak: false
}

var output = postcss(selector(options))
  .process(css)
  .css

var options = {
  extensions: {
    ':--any' : 'section, article, aside, nav'
  }
}

var output = postcss(selector(options))
  .process(css)
  .css;

var fs = require('fs')
var chokidar = require('chokidar')
var postcss = require('postcss')
var selector = require('postcss-custom-selectors')

var src = 'input.css'

console.info('Watching…\nModify the input.css and save.')

chokidar.watch(src, {
  ignored: /[\/\\]\./,
  persistent: true
}).on('all',
  function(event, path, stats) {
    var css = fs.readFileSync(src, 'utf8')
    var output = postcss(selector())
      .process(css)
      .css
    fs.writeFileSync('output.css', output)
  })

module.exports = function(grunt) {
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    postcss: {
      options: {
        processors: [
          require('autoprefixer-core')({ browsers: ['> 0%'] }).postcss, //Other plugin
          require('postcss-custom-selectors')(),
        ]
      },
      dist: {
        src: ['src/*.css'],
        dest: 'build/grunt.css'
      }
    }
  });

  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks('grunt-postcss');

  grunt.registerTask('default', ['postcss']);
}

var gulp = require('gulp');
var rename = require('gulp-rename');
var postcss = require('gulp-postcss');
var selector = require('postcss-custom-selectors')
var autoprefixer = require('autoprefixer-core')

gulp.task('default', function () {
    var processors = [
        autoprefixer({ browsers: ['> 0%'] }), //Other plugin
        selector()
    ];
    gulp.src('src/*.css')
        .pipe(postcss(processors))
        .pipe(rename('gulp.css'))
        .pipe(gulp.dest('build'))
});
gulp.watch('src/*.css', ['default']);