Regular Expressions 101

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/
https?:\/\/[\/\\]*(www\.)?
/
gm
http
matches the characters http literally (case sensitive)
s
matches the character s with index 11510 (7316 or 1638) literally (case sensitive)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
Match a single character present in the list below
[\/\\]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
\\ matches the character \ with index 9210 (5C16 or 1348) literally (case sensitive)
1st Capturing Group
(www\.)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
www
matches the characters www literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String