<!doctype html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Page creating a popup</title>
  </head>
  <body>
    <button id="pop" onclick='window.setTimeout(() => {window.open("popup_blocker_a.html", "a");}, 10);'>Open Popup</button>
  </body>
</html>
