带有特殊字符 (.) javascript 的 RegExp 字边界

Question

I want to find "USA" (without the quotes) if it is in a string as a whole word.

So good strings should be

U.S.A.
u.s.a.
U.S.A. is a great country
Is this U.S.A. ?

Bad string is

U.S.A.mnop
U.S.A

I tried using

/\bU\.S\.A\.\b/i

But strangely the one that works is - (But it fails for other countries and so not useful)

/\bU\.S\.A\.\B/i

This seems opposite of my understanding from documentation and have searched this and there are lots of similar problems but none of them helped me understand the issue. I think that the last "." is being consumed by \\b and hence not working but am still confused.

Can someone please help with explanation and the right search string ? It should also do proper word search of other strings without special characters.

Answer 1

You can check for the word boundary first (as you were doing), but the tricky part is at the end where you can't use the word boundary because of the . . However, you can check for a whitespace character at the end instead:

/\b(u\.s\.a\.)(?:\s|$)/gi

Check out the Regex101