Passing Date Field and Rid to my codepage

I am using the below code in a html code page but I need to pass my Date Field and my rid to this codepage. I am displaying the codepage in my form so that there is a countdown till due.


<p id="demo"></p>

<script>

var countDownDate = new Date("8-10-2019").getTime();


var x = setInterval(function() {


  var now = new Date().getTime();


  var distance = countDownDate - now;


  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);


  document.getElementById("demo").innerHTML = days + "d " + hours + "h "
  + minutes + "m " + seconds + "s ";


  if (distance < 0) {
    clearInterval(x);
    document.getElementById("demo").innerHTML = "EXPIRED";
  }
}, 1000);
</script>

The var countDownDate is where I need to get my fid 166 from what ever record I happen to open...

The code I am using to display the page is -

"<img data-url='" & [URL 1] & "'" &
" src onerror='(async () => {  var url = this.dataset.url;  this.outerHTML = '<iframe src=${url} width=155px height=50px></iframe>';})();'>"

Can anyone help?