Match group before nth character and after that

Question

I want to match everything before the nth character (except the first character) and everything after it. So for the following string

/firstname/lastname/some/cool/name

I want to match

Group 1: firstname/lastname
Group 2: some/cool/name

With the following regex, I'm nearly there, but I can't find the correct regex to also correctly match the first group and ignore the first /:

([^\/]*\/){3}([^.]*)

Note that I always want to match the 3rd forward slash. Everything after that can be any character that is valid in an URL.

Code Maniac · Accepted Answer · 2019-07-14T14:12:53.663

1

Your regex group are not giving proper result because ([^\/]*\/){3} you're repeating captured group which will overwrite the previous matched group Read this

You can use

^.([^/]+\/[^/]+)\/(.*)$

let str = `/firstname/lastname/some/cool/name`

let op = str.match(/^.([^/]+\/[^/]+)\/(.*)$/)

console.log(op)

edited Jul 14 '19 at 14:12

answered Jul 14 '19 at 13:06

Code Maniac

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Works. But I don't get why. How did you create this neat little graphic? – Stephan Jul 14 '19 at 13:41
@Stephan where you're facing problem to understand ? this little graphics is generated by [`Regex visualizer`](https://jex.im/regulex/) – Code Maniac Jul 14 '19 at 13:52
The more I look at it the more clear it is. The only thing missing now is the first two characters: ^. I guess they are used to ignore the first character. But how? – Stephan Jul 14 '19 at 14:04
@Stephan `^` means start of string and `.` means match anything except new line, since we don't want this to be included in our group so we kept it out of `()` – Code Maniac Jul 14 '19 at 14:06

score 0 · Answer 2 · answered Jul 14 '19 at 13:26

0

Ignoring the first /, then capturing the first two words, then capturing the rest of the phrase after the /.

^(:?\/)([^\/]+\/[^\/]+)\/(.+)

See example

answered Jul 14 '19 at 13:26

Yaelet

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The fourth bird · Answer 3 · 2019-07-14T14:16:44.253

The quantifier {3} repeats 3 times the capturing group, which will have the value of the last iteration.

The first iteration will match /, the second firstname/ and the third (the last iteration) lastname/ which will be the value of the group.

The second group captures matching [^.]* which will match 0+ not a literal dot which does not take the the structure of the data into account.

If you want to match the full pattern, you could use:

^\/([^\/]+\/[^\/]+)\/([^\/]+(?:\/[^\/]+)+)$

Explanation

^ Start of string
( Capture group 1
- [^\/]+/[^\/]+ Match 2 times not a / using a negated character class then a /
) Close group
\/ Match /
( Capture group 2
- [^\/]+ Match 1+ times not /
- (?:\/[^\/]+)+ Repeat 1+ times matching / and 1+ times not / to match the pattern of the rest of the string.
) Close group
$ End of string

Regex demo

Match group before nth character and after that

3 Answers3