get t.co destination URL

inline.js

document.addEventListener("mouseover", function tCo(ev) {
  const l = ev.target.closest("a[href^='https://t.co/']");
  // only run when target is a link with a t.co href
  if (l) {
    fetch(l.href, { method: "GET" })
      .then(function fetchResponse(res) { return res.text(); }) // get response html
      .then(function fetchHtml(html) {
        //console.log("html:", html);
        if (html) {
          const u = new DOMParser()  // convert response to node
            .parseFromString(html, 'text/html')
            .head       // head node
            .firstChild // noscript node
            .firstChild // meta node
            .content    // content attribute
            .replace(/^0;URL=/, ""); // strip off meta refresh prefix
         
          //console.log("url:", u);
          if (u) {
            // blink the link to reset status text
            const d = l.style.visibility;
            l.style.visibility = "hidden";
            setTimeout(function linkReset() {
              // change link's href and reset display
              l.href = u;
              l.style.visibility = d;
            }, 0);
          }
        }
      })
      .catch(function fetchError(ex) { console.log("error:", ex); });
  }
});
// replace hrefs of t.co links with target on hover (WIP)
// line #5 errors:
//Content Security Policy: The page’s settings blocked the loading of a resource at https://t.co/WcHpQjsp1X?amp=1 (“connect-src”).

t.co.js

const tDotCo = url => {
  return fetch(url, { method: "GET", redirect: "follow" })
    .then(res => res.text() ) // get response html
    .then(html => new DOMParser().parseFromString(html, 'text/html')
          .head       // head node
          .firstChild // noscript node
          .firstChild // meta node
          .content    // content attribute
          .replace(/^0;URL=/, "") // strip off meta refresh prefix
         );
};

// usage: 
// tDotCo("https://t.co/HlHXi6KF4Y?amp=1").then(f => console.log(f) )