css/css-counter-styles/cssom/cssom-name-setter.html

<!DOCTYPE html>
<title>CSSCounterStyleRule name setter</title>
<link rel="help" href="https://www.w3.org/TR/css-counter-styles-3/#the-csscounterstylerule-interface">
<link rel="author" href="mailto:xiaochengh@chromium.org">
<link rel="match" href="cssom-name-setter-ref.html">
<style id="sheet">
@counter-style foo {
  system: fixed;
  symbols: A B C;
}

@counter-style bar {
  system: fixed;
  symbols: '1' '2' '3';
}

@counter-style foo {
  system: fixed;
  symbols: X Y Z;
}
</style>

<ol style="list-style-type: foo; list-style-position: inside">
  <li></li>
  <li></li>
  <li></li>
</ol>

<ol style="list-style-type: bar; list-style-position: inside">
  <li></li>
  <li></li>
  <li></li>
</ol>

<script>
// Force layout update before changing the rule
document.body.offsetWidth;

// Change the last counter style name from 'foo' to 'bar'
const sheet = document.getElementById('sheet');
const rule = sheet.sheet.rules[2];
rule.name = 'bar';
</script>