why this code is not running, html error Options

[aqeel]

<center>
<p></p>
<button class="srd" id="btn"><b>click here to get code </b></button>
<a class="button" href="" id="download"> BR260695 </a>
<script>
var downloadButton = document.getElementById("download");
var counter = 19000;
var newElement = document.createElement("p");
newElement.innerHTML = "";
var id; downloadButton.parentNode.replaceChild(newElement, downloadButton);
function startDownload() { this.style.display = 'none';
id = setInterval(function () { counter--;
if (counter < 0) {newElement.parentNode.replaceChild(downloadButton,newElement);
clearInterval(id);
}
else { newElement.innerHTML = +counter.toString() + "<b>⏱️ WAIT A Second</b>."; } }, 0); };
var clickbtn = document.getElementById("btn");
clickbtn.onclick = startDownload;
</script>
</center>