代码示例:(标识:jsck_nodelist_length_p)
<!DOCTYPE html>
<html>
<style>
div {
  border: 1px solid black;
  padding: 15px;
}
</style>

<body>
<h1>Nodelist 对象</h1>

<h2>length 属性</h2>

<div id="myDIV">
  <p>I am a paragraph.</p>
  <p>I am a paragraph.</p>
  <p>I am a paragraph.</p>
</div>

<p>"myDIV" 中的 p 个元素为:</p>

<p id="demo"></p>

<script>
const div = document.getElementById("myDIV");
const list = div.querySelectorAll("p");
document.getElementById("demo").innerHTML = list.length;
</script>

</body>
</html>
运行结果: