W3School TIY
编辑您的代码：
<!DOCTYPE html> <html> <head> <style>.highlight{background-color: yellow}</style> <script type="text/javascript" src="../jquery/jquery.js"></script> </head> <body> <p><span>Look:</span> <span>This is some text in a paragraph.</span> <span>This is a note about it.</span></p> <script>$("p span").first().addClass('highlight');</script> </body> </html>
查看结果: