HTML 实体编码解码器
HTML 实体互转：&、尖括号、引号五个关键字符转义；named/十进制/十六进制实体解码，双层编码逐层还原。
Action
Escape non-ASCII as &#x…;
When are entities needed?
Inside HTML text, the characters & < > (and " / ' inside attributes) must be escaped so the browser parses them as text instead of markup. Encoding converts them to & < > " '. The checkbox additionally escapes every non-ASCII character (é → é) for legacy E-mail templates and old CMSes; uncheck it to keep Unicode intact and escape only the five markup characters. Decoding understands all named, decimal and hex numeric entities.
如何使用HTML 实体编码解码器
把不可信文本、HTML 片段或渲染后的内容粘贴进来：Encode 只转义五个关键字符（&、尖括号、引号），Decode 反向还原，多层编码连点两次即可逐层剥开。占位符示例演示了混排场景转义前后的差别。
用户输入进入 HTML 模板前先转义，就能挡住经典注入向量并保持标记合法。像 <div> 这种双层产物，一两次解码就恢复原貌，每个字符对应哪个实体全程可见。