Find duplicate styles

duplicate-css.js

const rules = Array.from(document.getElementsByTagName("style"))
  .map((el) => el.innerText.split("}"))
  .flat()
  .map((rule) => rule.trim())
  .filter((rule) => rule && !rule.startsWith("@"))
  .map((rule) => {
    return {
      selector: rule.split("{")[0].trim(),
      style: rule.split("{")[1].trim(),
    };
  });

const global = {};
const counts = { total: 0, rules: 0, selectors: 0 };

for (const { selector, style } of rules) {
  counts.total++;
  if (global[selector] === style) {
    console.log(`Duplicate rule: ${selector}`);
    counts.rules++;
  } else if (global[selector]) {
    console.log(`Duplicate selector: ${selector}`);
    counts.selectors++;
  } else {
    global[selector] = style;
  }
}

console.log(`Total duplicates`, counts);