custom-element-bootstrap.html

<!DOCTYPE html>
<html>
<head>
<title>Custom Elements: Bootstrap Example</title>
<meta name="author" title="Eugene Kashida" href="mailto:ekashida@gmail.com">
</head>
<body>
<script>

class MyCustomElement extends HTMLElement {
    constructor() {
        super();
    }
    connectedCallback() {
    }
    disconnectedCallback() {
    }
}

customElements.define('my-custom-element', MyCustomElement);
var instance = document.createElement('my-custom-element');
document.body.appendChild(instance);

</script>
</body>
</html>