正则表达式将特定路径与特定查询参数匹配

Question

I'm struggling with creating regex to match URL path with query param that could be in any place.

For example URLs could be:

/page?foo=bar&target=1&test=1 <- should match
/page?target=1&test=2 <- should match
/page/nested?foo=bar&target=1&test=1 <- should NOT match
/page/nested?target=1&test=2 <- should NOT match
/another-page?foo=bar&target=1&test=1 <- should NOT match
/another-page?target=1&test=2 <- should NOT match

where I need to target param target specifically on /page

This regex works only to find the param \\A?target=[^&]+&* .

Thanks!

UPDATE: It is needed for a third-party tool that will decide on which page to run an experiment. It only accepts setup on their dashboard with regular experssion so I cannot use code tools like URL parser.

Answer 1

General rule is that if you want to parse params, use URL parser, not a custom regex.

In this case you can use for instance:

# http://a.b/ is just added to make URL parsing work
url = new URL("http://a.b/page?foo=bar&target=1&test=1")
url.searchParams.get("target")
# => 1
url.pathname
# => '/page'

And then check those values in ifs:

url = new URL("http://a.b/page?foo=bar&target=1&test=1")

url = new URL("http://a.b/page?foo=bar&target=1&test=1")
if (url.searchParams.get("foo") && url.pathname == '/page' {
  # ...
}

See also:

• https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams
• https://developer.mozilla.org/en-US/docs/Web/API/URL

EDIT

If you have to use regex try this one:

\/page(?=\?).*[?&]target=[^&\s]*(&|$)

Demo

Explanation:

• \\/page(?=\\?) - matches path (starts with / then page then lookahead for ? )
• .*[?&]target=[^&\\s]*($|&) matches param name target :
  • located anywhere (preceded by anything .* )
  • [?&] preceded with ? or &
  • followed by its value (=[^&\\s]*)
  • ending with end of params ( $ ) or another param ( & )

Answer 2

If you're looking for a regex then you may use:

/\/page\?(?:.*&)?target=[^&]*/i

RegEx Demo

RegEx Details:

• \\/page\\? : Match text /page? :
• (?:.*&)? : Match optional text of any length followed by &
• target=[^&]* : Match text target= followed by 0 or more characters that are not &