Question

I read some tutorials about regex and I saw a sentence:

(?<=exp): Match any position following a prefix exp

For example, I have some strings:

Share

Care

If I want to find all string include "are", but "are" must follow "Sh": /(?<=Sh)are/i. Now only "Share" is matched, and matched index is 2 (match "are", not "Share" from "Share").

But Javascript don’t have this regex. How can I do like that in Javascript?

Thanks!

Answer 1

You can’t do it. There are no lookbehind assertions in Javascript’s implementation of regular expressions.

Alternatives

• In some situations you can instead use a grouping to capture what you actually wanted to match: /Sh(are)/i

• If you really need lookbehinds you could use a third-party regular expression library.

Related

• JavaScript: Is there a regular expression library that fully supports lookarounds?