index.html

<!doctype html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <link rel="icon" type="image/svg+xml" href="/vite.svg" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Vite + Vue + TS</title>
  <script>
    // patch the createElement to avoid options is nullish
    // var _createElement = window.document.createElement;
    // window.document.createElement = function (tagName, options) {
    //   if (options) {
    //     return _createElement.call(window.document, tagName, options);
    //   } else {
    //     return _createElement.call(window.document, tagName);
    //   }
    // }
  </script>
</head>

<body>
  <div id="app"></div>
  <script type="module" src="/src/main.ts"></script>
  <custom-element data-text="placed in html body"></custom-element>
</body>

</html>