Question

I am new at making regular expressions, and so this might just be a stupid oversight, but my regex (that aims to match URL’s) is not working. My goal was to have it match any urls like:

http://www.somewhere.com
somewhere.com
https://ww3.some_where-hi.com
www.goop.go/herp/derp.lol

The regex i built is below, however, it does not match a URL like http://t.co/GZhtBh6c, it stops matching at the number 6 (As determined by http://www.regexpal.com).

((http|https)://)?([a-z0-9]+\.)?[a-z0-9\-_]+.[a-z]+(/[a-z0-9\-_]*)*([a-z0-9\-_]*\.[a-z]+){0,1}

Can anyone tell me why this is not working? Also, I’m sure this is not the best solution. If you have a more elegant regex for this, I would love to see it.

P.S. This regex will be used with javascript.

Answer 1

Validate if a string holds a URL as specified in RFC 3986. Both absolute and relative URLs are supported.

This matches your provide sample and more. It also lets you extract the different parts of the url

^
(# Scheme
 [a-z][a-z0-9+\-.]*:
 (# Authority & path
  //
  ([a-z0-9\-._~%!$&'()*+,;=]+@)?              # User
  ([a-z0-9\-._~%]+                            # Named host
  |\[[a-f0-9:.]+\]                            # IPv6 host
  |\[v[a-f0-9][a-z0-9\-._~%!$&'()*+,;=:]+\])  # IPvFuture host
  (:[0-9]+)?                                  # Port
  (/[a-z0-9\-._~%!$&'()*+,;=:@]+)*/?          # Path
 |# Path without authority
  (/?[a-z0-9\-._~%!$&'()*+,;=:@]+(/[a-z0-9\-._~%!$&'()*+,;=:@]+)*/?)?
 )
|# Relative URL (no scheme or authority)
 ([a-z0-9\-._~%!$&'()*+,;=@]+(/[a-z0-9\-._~%!$&'()*+,;=:@]+)*/?  # Relative path
 |(/[a-z0-9\-._~%!$&'()*+,;=:@]+)+/?)                            # Absolute path
)
# Query
(\?[a-z0-9\-._~%!$&'()*+,;=:@/?]*)?
# Fragment
(\#[a-z0-9\-._~%!$&'()*+,;=:@/?]*)?
$

In javascript this becomes

if (/^([a-z][a-z0-9+\-.]*:(\/\/([a-z0-9\-._~%!$&'()*+,;=]+@)?([a-z0-9\-._~%]+|\[[a-f0-9:.]+\]|\[v[a-f0-9][a-z0-9\-._~%!$&'()*+,;=:]+\])(:[0-9]+)?(\/[a-z0-9\-._~%!$&'()*+,;=:@]+)*\/?|(\/?[a-z0-9\-._~%!$&'()*+,;=:@]+(\/[a-z0-9\-._~%!$&'()*+,;=:@]+)*\/?)?)|([a-z0-9\-._~%!$&'()*+,;=@]+(\/[a-z0-9\-._~%!$&'()*+,;=:@]+)*\/?|(\/[a-z0-9\-._~%!$&'()*+,;=:@]+)+\/?))(\?[a-z0-9\-._~%!$&'()*+,;=:@\/?]*)?(#[a-z0-9\-._~%!$&'()*+,;=:@\/?]*)?$/im.test(subject)) {
    // Successful match
} else {
    // Match attempt failed
}