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<!DOCTYPE html>
<html>
<head>
<style>
#ex1 {
  color: red;
}
</style>
</head>
<body>
<h1>getPropertyValue() 方法</h1>
​
<p>单击按钮可返回 color 属性的值。</p>
​
<button onclick="myFunction()">试一试</button>
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<div id="ex1">一些文本。</div>
​
<script>
function myFunction() {
  var declaration = document.styleSheets[0].cssRules[0].style;
  var propvalue = declaration.getPropertyValue("color");
  alert(propvalue);
}
</script>
​
</body>
</html>
​