Javascript正则表达式匹配字符串,除非前面加上反斜杠

Question

如何在Javascript中匹配U1234,而不是\ U1234？

我无法弄清楚如何不匹配单反斜杠.我能得到的最接近的是:

\[\\]{0}U[0-9]{4}\b

但这不起作用.有什么建议？

Answer 1

JavaScript肯定不支持lookbehind断言.在我看来,获得你想要的东西的下一个最佳方式是

(?:^|[^\\])(U[0-9]{4})

说明:

(?:          # non-capturing group - if it matches, we don't want to keep it
   ^         # either match the beginning of the string
   |         # or
   [^\\]     # match any character except for a backslash
)            # end of non-capturing group
(U\d{4})     # capturing group number 1: Match U+4 digits