<!DOCTYPE html>
<meta charset="utf-8">
<script>
  document.addEventListener("DOMContentLoaded", () => {
    document.getElementById("id_0").contentEditable = false;
    document.querySelector("[contenteditable]").focus();
    document.execCommand("insertLineBreak");
  })
</script>
<pre>
<ins id="id_0">
<map contenteditable>