CODEWITHSUNDEEP
javascriptregex
Bhumi Singhal
Bhumi Singhal

Reputation: 8297

Check for characters before and after a word

I need to have a one positive regex which combines all 3 of the following:

-- ^(.*)\.abc\.(.*)$
-- ^(.*)\.abc$
-- ^abc\.(.*)$

such that the below cases do not apply to the regex:

-- 123abc
-- .abc123
-- 123abc.

and the following fgive the positive result:

--.abc
--.abc.
--abc.

I know that the 3 conditions can be in ORed in a group. I am looking fr a better solutoin, probably using lookaheads.

I tried using backreferencing : /^.*([\.]*)abc\1.*$/ but then this is positive for negative cases as well.

Upvotes: 1

Views: 113

Answers (1)

anubhava
anubhava

Reputation: 784958

You can use this regex:

^(.*([.;]))?abc((?=[.;])\2.*)?$

RegEx Demo

RegEx Breakup:

  • ^: Start
  • (.*([.;]))?: start with anything followed by dot or semicolon (optional match). Note that we capture before abc in capture group #2
  • abc: match abc
  • ((?=[.;])\2.*)?: End with same character we captured before abc and anything following (optional match). Lookahead assertion is used to make sure we don't match empty back-reference \2
  • $: End

Upvotes: 2

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