Validate URL domain using regex - regex

Question

I'm trying to validate a URL in multiple formats.
EG:
https://www.google.com OK
http://www.google.com OK
www.google.com OK
htt://www.google.com
://www.google.com
https://google.com OK
http\\www.google.com
http:\\www.google.com
http:\\www.google.com
http://computerName/abc/MenuItems.aspx OK
https://computerName/abc/MenuItems.aspx OK
http://www.a.com/abc/ms.aspx?Id=13&(Not.Licensed.For.Production)= OK
http://www.a.com/abc/ms.aspx?Id=13 OK
I'm using this regex
^(?:https?:\/\/(?:www\.)?|www\.)[a-z0-9]+(?:[a-zA-Z0-9_\-/\.]+)*(?::[0-9]{1,5})?(?:\/[a-z0-9]+)*(?:\.[a-z]{2,5})?$
But the last two items aren't ok. How can I also validate for urls without www and for eg.(.com)
I tried to removed the part (that I think validates the .com but without success.
It's almost working but found a new cases last two that don't work
Here's my sample https://regex101.com/r/w3dQSl/5

Answer 1

For your example links, you could use
^https?:\/\/[a-z0-9]+(?:[-.][a-z0-9]+)*(?::[0-9]{1,5})?(?:\/[^\/\r\n]+)*\.[a-z]{2,5}(?:[?#]\S*)?$
The pattern will match:
^ Start of string
https?:\/\/ Match the protocol with optional s and ://
[a-z0-9]+ Match 1+ times any of the listed
(?:[-.][a-z0-9]+)* Repeat 0+ times any of the listed preceded by a - or .
(?::[0-9]{1,5})? Optionally match : and 1-5 digits
(?:\/[^\/\r\n]+)* Repeat 0+ times / and any char except /
\.[a-z]{2,5} Match a . and 2-5 times a char a-z
(?:[?#]\S*)? Optionally match either ? or # and 0+ times any non whitespace char
$ End of string
Regex demo

Answer 2

You ought to think about which URLs you try to match, but for your examples, this does the job and is also simpler than the inital regex you provided:
^(https?://)?(www\.)?[a-zA-Z0-9-]+[a-zA-Z0-9_\-/\.\?=\&\(\)]+$
Optionally you can make some of the groups non-capturing by adding ?: after the opening parentheses.
Debuggex Demo