W3School TIY Editor
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<html> <head> <script type="text/javascript" src="/jquery/jquery.js"></script> <script type="text/javascript"> $(document).ready(function(){ $(".btn1").click(function(){ $("<b>Hello World!</b>").prependTo("p"); }); }); </script> </head> <body> <p>This is a paragraph.</p> <p>This is another paragraph.</p> <button class="btn1">在每个 p 元素的开头插入文本</button> </body> </html>