​x
 
<!DOCTYPE html>
<html>
<head>
<style>
h1 {
  color: red;
  font-size: 50px;
}
</style>
​
<script>
function myFunction() {
  var s = document.styleSheets[0].rules[0].style;
  var ruleObj = s.parentRule;
  document.getElementById("demo").innerHTML = ruleObj.cssText;
}
</script> 
</head>
<body>
​
<h1>parentRule 属性</h1>
​
<p>parentRule 属性返回 CSSRule 对象，表示指定的样式声明的 CSS 规则。</p>
​
<button onclick="myFunction()">显示 CSS 规则</button>
​
<p id="demo"></p>
​
</body>
</html>
​