​x
 
<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
  $("button").click(function(){
    $("p").css("color",function(){
    return "red";
    });
  });
});
</script>
</head>
​
<body>
<p>This is a paragraph.</p>
<p>This is another paragraph.</p>
<button>设置所有 p 元素的 color 属性</button>
</body>
</html>
​