命名反向引用：\k<名称>

¥Syntax

\k<name>

¥Parameters

name

群组的名称。必须是有效的 identifier 并引用现有的命名捕获组。

¥Description

命名反向引用与普通反向引用非常相似：它引用捕获组匹配的文本并匹配相同的文本。不同之处在于你通过名称而不是数字来引用捕获组。这使得正则表达式更具可读性并且更易于重构和维护。

¥Named backreferences are very similar to normal backreferences: it refers to the text matched by a capturing group and matches the same text. The difference is that you refer to the capturing group by name instead of by number. This makes the regular expression more readable and easier to refactor and maintain.

在 Unicode 不识别模式 中，如果正则表达式至少包含一个命名捕获组，则序列 \k 仅启动命名反向引用。否则，它是 身份逃避，与文字字符 k 相同。这是 已弃用的 Web 兼容性语法，你不应该依赖它。

¥In Unicode-unaware mode, the sequence \k only starts a named backreference if the regex contains at least one named capturing group. Otherwise, it is an identity escape and is the same as the literal character k. This is a deprecated syntax for web compatibility, and you should not rely on it.

/\k/.test("k"); // true

¥Examples

¥Pairing quotes

以下函数匹配字符串中的 title='xxx' 和 title="xxx" 模式。为了确保引号匹配，我们使用反向引用来引用第一个引号。访问第二个捕获组 ([2]) 返回匹配引号字符之间的字符串：

¥The following function matches the title='xxx' and title="xxx" patterns in a string. To ensure the quotes match, we use a backreference to refer to the first quote. Accessing the second capturing group ([2]) returns the string between the matching quote characters:

function parseTitle(metastring) {
  return metastring.match(/title=(?<quote>["'])(.*?)\k<quote>/)[2];
}

parseTitle('title="foo"'); // 'foo'
parseTitle("title='foo' lang='en'"); // 'foo'
parseTitle('title="Named capturing groups\' advantages"'); // "Named capturing groups' advantages"

¥See also

• 组和反向引用 指南
• 正则表达式
• 捕获组：(...)
• 命名捕获组：(?<name>...)
• 反向引用：\1、\2