SyntaxError: invalid named capture reference in regular expression

消息

SyntaxError: Invalid regular expression: /\k<x>/u: Invalid named capture referenced (V8-based)
SyntaxError: invalid named capture reference in regular expression (Firefox)
SyntaxError: Invalid regular expression: invalid \k<> named backreference (Safari)

SyntaxError: Invalid regular expression: /\k/u: Invalid named reference (V8-based)
SyntaxError: invalid named reference in regular expression (Firefox)
SyntaxError: Invalid regular expression: invalid escaped character for Unicode pattern (Safari)

错误类型

哪里出错了？

您正在使用转义序列\k，它被解析为命名反向引用，但\k要么语法无效，要么在模式中没有引用命名捕获组。

只有当模式包含命名捕获组或模式是Unicode 感知的时候，\k才开始一个命名反向引用；否则，它是字符k的恒等转义。

示例

无效案例

/\k<x>/u; // Does not refer to a named capture group
/(?<x>.+)\k<y>/u; // Does not refer to an existing named capture group
/(?<x>.+)\k{x}/u; // Invalid syntax

有效情况

/(?<x>.+)\k<x>/u; // Refers to an existing named capture group

另见

• 正则表达式
• 命名反向引用：\k<name>
• 命名捕获组：(?<name>...)