Regular Expressions 101

Pro

\Astart of string

Group 1((https?:\/\/(localhost:3000|blog\.example\.com))?\/posts\/(?<post_id>\S+?))?

?repeats the group contents below at most once:

Group 2(https?:\/\/(localhost:3000|blog\.example\.com))?

?repeats the group contents below at most once:

httpthe literal text http (case sensitive)

s?optionally matches the literal s (115₁₀ / 163₈ / 73₁₆) (case sensitive)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 3(localhost:3000|blog\.example\.com)

1st Alternativelocalhost:3000

localhost:3000the literal text localhost:3000 (case sensitive)

2nd Alternativeblog\.example\.com

blogthe literal text blog (case sensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

examplethe literal text example (case sensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

comthe literal text com (case sensitive)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

poststhe literal text posts (case sensitive)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group post_id(?<post_id>\S+?)

\S+?any non-whitespace character, repeated at least once

Group fragment(?<fragment>#(comment-(?<comment_id>\d+)|\S+?)?)?

?repeats the group contents below at most once:

#the literal # (35₁₀ / 43₈ / 23₁₆)

Group 6(comment-(?<comment_id>\d+)|\S+?)?

?repeats the group contents below at most once:

1st Alternativecomment-(?<comment_id>\d+)

comment-the literal text comment- (case sensitive)

Group comment_id(?<comment_id>\d+)

\d+a digit, repeated at least once

2nd Alternative\S+?

\S+?any non-whitespace character, repeated at least once

\zend of string

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

\A((https?:\/\/(localhost:3000|blog\.example\.com))?\/posts\/(?<post_id>\S+?))?(?<fragment>#(comment-(?<comment_id>\d+)|\S+?)?)?\z

New

http://blog.example.com/posts/foo#comment-123

http://blog.example.com/posts/foo#comment-123