W3School TIY Editor
W3School 在线教程
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<!DOCTYPE html> <html> <head> <script> var txt = ""; function message() { try { adddlert("Welcome guest!"); } catch(err) { txt = "此页面出错。\n\n"; txt += "单击“确定”继续查看此页面，\n"; txt += "或取消以返回主页。\n\n"; if(!confirm(txt)) { document.location.href = "https://www.w3school.org.cn/"; } } } </script> </head> <body> <input type="button" value="查看消息" onclick="message()" /> </body> </html>