How to match with new RegExp exactly

Question

I have this string:

var str = "https://www.mysite.se/this-match?ba=11"

I need to match it exactly (between / and ?), so only this-match matches, not this-ma or anything (shorter) that is contained in this-match. I.e:

var myre = new RegExp('\/this-ma\?');

Still matches:

myre.exec(str)[0]
"/this-ma"

How can I avoid that a shorter string contained in this-match does give a match?

If you want `this-match` to be the only match then why are you supplying `this-ma` ? — Neil Lunn, Jun 06 '17 at 08:44
@NeilLunn Because sometimes I have similar strings, which could be contained in `this-match` — user1665355, Jun 06 '17 at 08:45
Nope I don't get it. Exact match or Similar strings. Which one is it? Not really clear. — Neil Lunn, Jun 06 '17 at 08:46
If I understand correct you are looking a way to get `this-match` using regex. If yes, you can check [this](https://regex101.com/r/WbSMsE/1) — Rajesh, Jun 06 '17 at 08:49

Sergio Tulentsev · Accepted Answer · 2017-06-06T08:47:44.380

2

The definition of your regex is wrong. You'd think that \? would match literal ? character, instead of being non-greedy modifier. Not true. Quite the opposite, in fact.

var myre = new RegExp('\/this-ma\?');
> /\/this-ma?/

The backslash here works within the string literal, and outputs single ? to regex, which becomes non-greedy modifier. Use the regex literal.

var myre = /\/this-ma\?/

edited Jun 06 '17 at 08:47

answered Jun 06 '17 at 08:45

Sergio Tulentsev

226,338
43
373
367

you can also use also use a double backslash when you define the pattern in a string. – Casimir et Hippolyte Jun 06 '17 at 08:47
@Sergio Tulensev Like this? `var myre = new RegExp('\/this-ma\\?');` – user1665355 Jun 06 '17 at 08:48
@user1665355: yes, if you're building regexes dynamically. If it's static, you should prefer regex literals – Sergio Tulentsev Jun 06 '17 at 08:49
yes or `new RegExp('/this-ma\\?')` – Casimir et Hippolyte Jun 06 '17 at 08:49
@SergioTulentsev Thanks! It works. – user1665355 Jun 06 '17 at 08:50

How to match with new RegExp exactly

1 Answers1