<!DOCTYPE html>
<html>
<head>
  <script>
    window.addEventListener("load", () => {
      const heading = document.getElementById("heading")
      const input = document.createElementNS("http://www.w3.org/1999/xhtml", "input")
      heading.appendChild(input)
      const selection = window.getSelection()
      const range = new Range()
      range.setStartBefore(input)
      heading.contentEditable = true
      document.execCommand("selectAll", false, null)
      document.designMode = "on"
      selection.addRange(range)
      range.setEndBefore(heading)
      range.setEndAfter(heading)
      document.execCommand("insertImage", false, "wss://:pass@[::1]$/")
    })
  </script>
</head>
<h4 id="heading"></h4>
<!-- COMMENT -->
</html>
