Capturer des arbres MIME possibles avec Regex - Stack Overflow

I'm trying to make a capture group to grab the tree portion of a MIME type. i already know that the input text is a MIME type. As examples:

MIME Type Matched portion

text/plain                           -> No match
application/x-deb                    -> "x"
application/vnd.google-earth.kml+xml -> "vnd"
application/x.example123             -> "x"
application/prs.vanity               -> "prs"
application/prs-vanity               -> No match

Currently, I have /(?:(prs|vnd|x)\.)|(x-)?, but I'm trying to consolidate it into a single capture group. Is this possible?

The only other try I've done is /(?:(prs|vnd|x)[\.-])?, but that matches, for example, application/vnd-badly-made as vnd instead of properly not matching anything.

One possible approach: match something that's preceded by application/ and is...

• either x symbol followed by -,


• or a group of letters followed by .

... with this pattern:

/(?<=application\/)(?:x(?=-)|[a-z]+(?=\.))/

Demo. If lookbehind is not an option, use capturing group:

/application\/(x(?=-)|[a-z]+(?=\.))/

What about this:

application/(?:(prs(?!-)|vnd(?!-)|x))(?=\.|-)

It matches all your cases.

I'm trying to make a capture group to grab the tree portion of a MIME type. i already know that the input text is a MIME type. As examples:

MIME Type Matched portion

text/plain                           -> No match
application/x-deb                    -> "x"
application/vnd.google-earth.kml+xml -> "vnd"
application/x.example123             -> "x"
application/prs.vanity               -> "prs"
application/prs-vanity               -> No match

Currently, I have /(?:(prs|vnd|x)\.)|(x-)?, but I'm trying to consolidate it into a single capture group. Is this possible?

The only other try I've done is /(?:(prs|vnd|x)[\.-])?, but that matches, for example, application/vnd-badly-made as vnd instead of properly not matching anything.

One possible approach: match something that's preceded by application/ and is...

• either x symbol followed by -,


• or a group of letters followed by .

... with this pattern:

/(?<=application\/)(?:x(?=-)|[a-z]+(?=\.))/

Demo. If lookbehind is not an option, use capturing group:

/application\/(x(?=-)|[a-z]+(?=\.))/

What about this:

application/(?:(prs(?!-)|vnd(?!-)|x))(?=\.|-)

It matches all your cases.

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