如何在 contenteditable div 中的特定位置添加/插入/更新文本？

<div id="content" contenteditable="true">
  <p>Hello, world!</p>
</div>

<script>
  var content = document.getElementById("content");
  content.innerHTML = "<p>Hello, world!</p>";
</script>

<div id="content" contenteditable="true">
  <p>Hello, world!</p>
</div>

<script>
  var content = document.getElementById("content");
  content.textContent = "Hello, world!";
</script>

<div id="content" contenteditable="true">
  <p>Hello, world!</p>
</div>

<script>
  var content = document.getElementById("content");
  var range = document.createRange();
  range.selectNodeContents(content);
  range.collapse(false);
  var selection = window.getSelection();
  selection.removeAllRanges();
  selection.addRange(range);
  content.focus();
</script>