​x
 
<!DOCTYPE html>
<html>
<head>
<style>
body {
  background-color: yellow; 
  color: red;
}
</style>
</head>
<body>
​
<p>单击按钮可显示该文档的 style 属性。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
<script>
function myFunction() {
  var x = document.getElementsByTagName("STYLE")[0];
  document.getElementById("demo").innerHTML = x.innerHTML;
}
</script>
​
</body>
</html>
​