Regex - check if input still has chances to become matching

Question

We\'ve got such regexp:

var regexp = /^one (two)+ three/;

So only string like \"one two three\" or \"one two three four\

Answer 1

EDIT: after you edited your post the clarify, this answer might not be relevant to your specific question. Leaving it here for reference.

---

Inside the regex itself, on the subject of failing quickly once you know you won't find anything:

The anchor in your regex means that once the regex engine reaches the h of three, it will stop looking for matches and not try to start a match on the second character. On this case, I don't think you can do better than that (but it's already linear complexity, so not so bad).

On other cases I believe you have some usual best practices to learn in order to fail as quickly as possible when you know a match can't be found anymore.

You can look at possessive quantifiers if you don't already know them, but there are many other tricks...