代码示例:(标识:jsck_node_isdefaultnamespace)
<!DOCTYPE html>
<html>
<body>

<h1>Element 对象</h1>

<h2>isDefaultNamespace 属性</h2>

<p>指定的命名空间是默认的吗?</p>

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

<script>
const element = document.documentElement;
let answer = element.isDefaultNamespace("http://www.w3.org/1999/xhtml"); 
document.getElementById("demo").innerHTML = answer;
</script>

</body>
</html>
运行结果: