奇怪的结果与简单的正则表达式

Question

I'm working on regular expressions right now and experience a strange behavior:

The following regex accepts Q-123456-789 or q-123456-789

params: '^\\q\\-\\d{6}\\-\\d{3}$|^\\Q\\-\\d{6}\\-\\d{3}$'

The following regex accepts R-123456-789 but not r-123456-789

params: '^\\r\\-\\d{6}\\-\\d{3}$|^\\R\\-\\d{6}\\-\\d{3}$'

(I simply replaced q by r and Q by R )

Answer 1

Because:

\\r matches a carriage return

but \\q matches literal q only.

Btw your regex is using excessive escaping, it should be without \\\\ ie

"^[qQ]-\\d{6}-\\d{3}$"

OR

"^[rR]-\\d{6}-\\d{3}$"

Answer 2

\\r matches a carriage return (0x0D - a non printable character), not the r character. whereas \\q does match the character q .

If you want to match r or R , simply replace them in a character class: ^[rR] .

Answer 3

Try [r] for exact match instead of \\r for expected result

Try this:

^[rR]-\d{6}\-\d{3}$

Use https://regex101.com/#javascript for testing