App下载
实例代码( Tip: 登录后体验更佳 )
<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>(w3cschool.cn)</title>
<style>
.marked {
color: red;
font-size: 30px;
}
</style>
<script src="https://7npmedia.w3cschool.cn/w3.js"></script>
<body>
<h2> HTML W3.JS</h2>
<p> marked h2.</p>
<p><button onclick="w3.addClass('h2','marked')"></button></p>
<div id="London" class="city">
<h2></h2>
<p>.</p>
</div>
<div id="Paris" class="city">
<h2></h2>
<p>.</p>
</div>
<div id="Tokyo" class="city">
<h2></h2>
<p>.</p>
</div>
</body>
</html>
 
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运行结果