RegEx在字符串的开头或字符串本身的开头匹配符号

Question

I'm trying to come up with a regex that would catch a TLD in a group of subdomains. So I have this:

/\.?google\.com$/i

That should do the following matches:

sgoogle.com            -- no match
google.com             -- match
maps.google.com        -- match
job_s.map.google.com   -- match
place.google.com.eu    -- no match

This works, except for the first one, ie sgoogle.com that it matches as well, which it shouldn't.

So I'm curious, is there a way to specify where I do \\.? to match either a dot or the beginning of string?

Answer 1

You're almost there. Literally, your requirement would be:

(?:^|\.)google\.com$

But depending on your needs, this could be better (or not, you tell me):

\bgoogle\.com$

The \\b means word boundary .