Simple feature detection for CSS :has()

checkCssHas.js

(function() {
  const s = document.createElement('style');
  s.textContent = `.supportsHas:has(p):after {content: "hasHas";}`;
  document.head.appendChild(s);
  const supportsHas = document.createElement('div');
  supportsHas.classList.add('supportsHas');
  const p = document.createElement('p');
  supportsHas.appendChild(p);
  document.body.appendChild(supportsHas);

  if (getComputedStyle(document.body, 'after')?.content === '"hasHas"') {
    console.log('supports :has()');
  } else {
    console.log('does not suport :has()');
  }

  document.head.removeChild(s);
  document.body.removeChild(supportsHas);
}());

CSS.supports('selector(html:has(body))');