InsertLinkFileInfo Bookmarklet

javascript:
/*InsertLinkFileInfo*/
((l, i, a) => {
  if (!document || !document.body || document.body.dataset.ilfi) return;
  document.body.dataset.ilfi = 1;
  if (!(l = document.querySelectorAll("A")).length) {
    delete document.body.dataset.ilfi;
    alert("No link found.");
    return
  }
  i = 0;
  (function pr(s, u) {
    while (a = l[i++]) {
      if (a.pathname.substr(-1) !== "/") {
        fetch(a.href, {method: "HEAD", redirect: "error", keepalive: true}).catch(e => {
          a.insertAdjacentHTML("afterend", ` [NetErr]`)
          pr()
        }).then((r, d) => {
          if (r.status < 400) {
            if (!isNaN(s = parseInt(r.headers.get("Content-Length")))) {
              if (s > 1023) {
                if ((s /= 1024) > 1023) {
                  if ((s /= 1024) > 1023) {
                    if ((s /= 1024) > 1023) {
                      s = (s / 1024).toFixed(0) + "TB"
                    } else s = s.toFixed(0) + "GB"
                  } else s = s.toFixed(0) + "MB"
                } else s = s.toFixed(0) + "KB"
              }
            } else s = "???";
            if (d = r.headers.get("Last-Modified")) {
              s += ", " + (new Date(d)).toLocaleString()
            } else s+= ", ???";
            s = ` [${s}]`
          } else s = ` [Err${r.status}]`;
          a.insertAdjacentHTML("afterend", s);
          pr()
        });
        return
      }
    }
    delete document.body.dataset.ilfi
  })()
})()