CustomElementRegistry is an experimental interface. <!DOCTYPE html>
<html>
<head>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<title>CustomElementRegistry</title>
<script>
class tq84 extends HTMLElement {
constructor() {
alert ('tq84 ctor');
}
}
function main() {
customElements.define('tq-84', tq84);
}
</script>
</head>
<body onload='main()'>
<p><tq-84> follows:</p>
<tq-84>
</tq-84>
</body>
</html>
window.customElements