remove unused css (PurgeCss) in Create React App without ejecting

purge-css.js

const { PurgeCSS } = require("purgecss");
const fs = require("fs");

(async () => {
  const results = await new PurgeCSS().purge("./purgecss.config.js");

  results.forEach((result) => {
    const { css, file } = result;

    fs.stat(file, (error, originalFileStats) => {
      // console.log(originalFileStats);
      fs.writeFileSync(file, css);
      const newFileStats = fs.statSync(file);
      console.log("\x1b[32m", `PurgeCSS saved ${Math.round((originalFileStats.size - newFileStats.size) / 1000)}kb on ${file}`);
    });
  });
})();

PurgeCss in Create React App without ejecting

//package.json
{
  ...
  "devDependencies": {
     ...
    "purgecss": "^3.0.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build && npm run purge-css",
    "purge-css": "node ./purge-css",
    "build:RCA": "react-scripts build",
    ...
  },
  ...
}

purgecss.config.js

module.exports = {
  content: ['./build/index.html', './build/**/*.js', './build/**/*.html'],
  css: ['./build/**/*.css'],
  fontFace: true,
  keyframes: true,
  variables: true
}