x
 
<!DOCTYPE html>
<html>
<body>
<h1>Element 对象</h1>
<h2>nodeValue 属性</h2>
<button>试一试</button>
<p>第一个 button 元素的节点值为:</p>
<p id="demo"></p>
<script>
const element = document.getElementsByTagName("BUTTON")[0];
let value = element.childNodes[0].nodeValue;  
document.getElementById("demo").innerHTML = value;
</script>
</body>
</html>