CODE EXAMPLE FOR JAVASCRIPT

javascript create anchor link

const createAnchorLink = (id) => {
  const anchor = document.createElement("a");
  anchor.className = "anchor-link";
  anchor.href = "#" + id;
  return anchor;
};

window.onload = () => {
  let increment = 0;
  [...document.querySelectorAll("h1, h2, h3, #spec > ol > li > p")].forEach(
    (el) => {
      if (el.id) {
        const anchorLink = createAnchorLink(el.id);
        el.insertBefore(anchorLink, el.firstChild);
      } else {
        increment++;
        el.parentElement.id = "spec-item-" + increment;
        const anchorLink = createAnchorLink(el.parentElement.id);
        el.parentElement.insertBefore(anchorLink, el);
      }
    }
  );

  const hash = window.location.hash;
  if (hash) {
    const targetElTop = document.querySelector(hash).offsetTop;
    window.scrollTo(0, targetElTop);
  }
};