Compressor the rules in CSS

compresor.js

const css = require('css');
const fs = require('fs');
const path = require('path');

const fileIn = path.join(__dirname, 'style.css');
const fileOut = path.join(__dirname, 'out.css');

Object.fromEntries = Object.fromEntries || ((x) => x.reduce((p,c) => {p[c[0]]=c[1];return p;},{}));

fs.readFile(fileIn, {encoding: 'utf-8'}, function(err,data){
  if (!err) {
    let cssIn = css.parse(data);
    let cssOut = JSON.parse(JSON.stringify(cssIn));
    let exlcude = [];

    cssOut.stylesheet.rules = [];
    for (let i = 0; i < cssIn.stylesheet.rules.length; i++) {
      if(cssIn.stylesheet.rules[i].type == 'rule' ){
        if(!exlcude.find(e => JSON.stringify(e) == JSON.stringify(cssIn.stylesheet.rules[i]))){
          let style = cssIn.stylesheet.rules[i].selectors.sort((a, b) => a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0);
           let same = cssIn.stylesheet.rules.filter(rule => JSON.stringify(
                (rule.selectors || [] ).sort((a, b) => a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0)) === JSON.stringify(style));

           cssOut.stylesheet.rules.push({
            type: 'rule',
            declarations : [].concat.apply([], same.map(e => e.declarations )),
            selectors : cssIn.stylesheet.rules[i].selectors
          });

          exlcude = exlcude.concat(same);
        }
      } else {
        cssOut.stylesheet.rules.push(cssIn.stylesheet.rules[i]);
      }
    }

    console.log("css:same", cssIn.stylesheet.rules.length, cssOut.stylesheet.rules.length);

    cssIn = JSON.parse(JSON.stringify(cssOut));
    cssOut = JSON.parse(JSON.stringify(cssOut));
    exlcude = [];

    cssOut.stylesheet.rules = [];

    for (let i = 0; i < cssIn.stylesheet.rules.length; i++) {
      if(cssIn.stylesheet.rules[i].type == 'rule' ){
        if(!exlcude.find(e => JSON.stringify(e) == JSON.stringify(cssIn.stylesheet.rules[i]))){
          let style = Object.fromEntries(cssIn.stylesheet.rules[i].declarations.map(e => ([ e.property, e.value ])).sort((a, b) => a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0));
          let same = cssIn.stylesheet.rules.filter(rule => JSON.stringify(Object.fromEntries(
                (rule.declarations || [] ).map(
                  e => ([ e.property, e.value ])).sort((a, b) => a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0))) === JSON.stringify(style));
          cssOut.stylesheet.rules.push({
            type: 'rule',
            declarations : cssIn.stylesheet.rules[i].declarations,
            selectors : [].concat.apply([], same.map(e => e.selectors ))
          });
          exlcude = exlcude.concat(same);
        }
      } else {
        cssOut.stylesheet.rules.push(cssIn.stylesheet.rules[i]);
      }
    }

    console.log("css:rules", cssIn.stylesheet.rules.length, cssOut.stylesheet.rules.length);

    cssIn = JSON.parse(JSON.stringify(cssOut));
    cssOut = JSON.parse(JSON.stringify(cssOut));
    exlcude = 0;
    let exlcd = 0;

    cssOut.stylesheet.rules = [];

    for (let i = 0; i < cssIn.stylesheet.rules.length; i++) {
      if(cssIn.stylesheet.rules[i].type == 'rule' ){
        var declarations = [];
        exlcude += cssIn.stylesheet.rules[i].declarations.length ;

        for (let z = cssIn.stylesheet.rules[i].declarations.length - 1; z >= 0; z--) {
          if(!declarations.find(e => e.property === cssIn.stylesheet.rules[i].declarations[z].property)){
            declarations.push( cssIn.stylesheet.rules[i].declarations[z] );
          } else {
            exlcd++;
          }
        }

        cssOut.stylesheet.rules.push({
          ...cssIn.stylesheet.rules[i],
          declarations,
        });
      } else {
        cssOut.stylesheet.rules.push(cssIn.stylesheet.rules[i]);
      }
    }

    console.log("css:declarations", exlcude, exlcd);

    fs.writeFile(fileOut, css.stringify(cssOut), function(err) {
      if(err) {
        return console.log(err);
      }
      console.log("The file was saved!");
    });

  } else {
    console.log(err);
  }
});

selector.js

const browserless = require('browserless')();

const DOMAIN = 'http://URL.EXT/';
const AMP = 'amp';
const URLS = [
  'my-url-test'
];

var result = {};

var testers = [
  (line) => /\{$/.test(line),
  (line) => !/^\@media/.test(line),
  (line) => !/\/\*/.test(line)
];

var clean = [
  (line) => line.split(/\,/gim),
  (line) => line.replace(/\{$/gim, ''),
  (line) => line.replace(/\:\w+/gim, ''),
  (line) => [ line ].concat(line.split(/\,|\s|\>|\+|\~/gim))
];

const nextOpen = browserless
  .evaluate(async (page, response) => {
    Array.concatAll = (args) => {
      return (args) = [].concat(...args);
    }

    Array.Flatten = (arr) => {
      return Array.concatAll(arr.map(x => Array.isArray(x) ? Array.Flatten(x) : x ))
    };

    try {
      const styleHandle = await page.$('style[amp-custom]');
      const innerHTML = await page.evaluate(body => body.innerHTML, styleHandle);
      const file = innerHTML.split(/\n/gim);
      let lines = [];

      for (let line = 0; line < file.length; line++) {
        if(testers.every(e => e(file[line]))){
          let select = [ file[line] ];
          let last = [];

          for (let i = clean.length - 1; i >= 0; i--) {
            let array = select.map((e) => clean[i](e));
            select = Array.Flatten(array.filter((e, i) => e && array.indexOf(e) == i ));
          }

          let invalids = 0;

          for (var i = select.length - 1; i >= 0; i--) {
            try {
              result[select[i]] = result[select[i]] || 1;
              let me = await page.$(select[i]);

              if(me){
               result[select[i]]++;
              }
            } catch(e){
              invalids++;
              //console.log("catch");
            } finally {
              //console.log("finally");
            }
          }
          lines.push(invalids);
        }
      }

      return Promise.resolve(lines);
    } catch(e){
      console.log("log", e);
      return Promise.resolve([]);
    }
  });

;(async () => {
  for (var i = URLS.length - 1; i >= 0; i--) {
    try {
      const info = await nextOpen( DOMAIN + URLS[i] + AMP);
      console.log("Info", URLS[i], info.reduce((accumulator, currentValue) => accumulator + currentValue, 0));
    } catch(e) {
      console.log("Fail", URLS[i]);
    }
  }

  console.log('--- Result ---');
  console.log(JSON.stringify(result, null, '\t'));
})();