SyntaxError: invalid named capture reference in regular expression

訊息

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)

錯誤型別

哪裡出錯了？

您正在使用轉義序列\k，它被解析為命名反向引用，但\k要麼語法無效，要麼在模式中沒有引用命名捕獲組。

只有當模式包含命名捕獲組或模式是Unicode 感知的時候，\k才開始一個命名反向引用；否則，它是字元k的恆等轉義。

示例

無效案例

/\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

有效情況

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

另見

• 正則表示式
• 命名反向引用：\k<name>
• 命名捕獲組：(?<name>...)