​x
 
<!DOCTYPE html>
<html>
<head>
<base id="myBaseId" href="http://www.w3school.com.cn/jsref/" />
</head>
<body>
​
<p>单击按钮以显示 base 元素的 href 属性的值。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
<script>
function myFunction() {
  var x = document.getElementById("myBaseId").href;
  document.getElementById("demo").innerHTML = x;
}
</script>
​
</body>
</html>
​
​