Demo Popup Window

<a href="https://www.html-code-generator.com/" id="open-popup">open popup</a>

<script>
const id_open_popup = document.getElementById("open-popup");
id_open_popup.addEventListener("click", function(event){
  event.preventDefault();
  let url = this.href;
  let window_size = 'width=800,height=500,left=0,top=0';
  popupWindow = window.open(url, 'myWindow', window_size);
});
</script>

<a href="https://www.html-code-generator.com/" id="open-center-popup">open center popup</a>

<script>
const id_center_open_popup = document.getElementById("open-center-popup");
id_center_open_popup.addEventListener("click", function(event){
  event.preventDefault();
  const url = this.href;
  const width = 800;
  const height = 500;
  const left = (screen.width - width) / 2;
  const top = (screen.height - height) / 2;
  const window_size = 'width='+width+',height='+height+',left='+left+',top='+top;
  popupWindow = window.open(url, 'myWindow', window_size);
});
</script>