Can someone explain me how this regex works?

[ILM]

you can try to review this challenge:

freeCodeCamp.org

you can also take a look at this explanation:

Can Anyone Explain. What is the "$1 $2" in first replace statement of solution 1?

str = str.replace(/([a-z])([A-Z])/g, "$1 $2") ↑ ↑ $1 $2 So if str is “aB”, that matches (lowercase a-z character followed by uppercase A-Z character), first capturing group is the lowercase, second capturing group is the uppercase, so it will be replaced with “a B” So if str is “helloThere”, that matches (there is lowercase a-z character followed by uppercase A-Z character), first capturing group is the lowercase, second capturing group is th…

and this follow up:

Regex:Capturing Groups

No, so the regex finds any* pairs of a lowercase letter ([a-z]) directly followed by an uppercase letter ([A-Z]). The pattern is /[a-z][A-Z]/, that’s two characters. So in the string “AllThe-small Things”, there is one instance of that, “lT”: AllThe-small Things ↑ here The pattern to find each of those is wrapped in brackets /([a-z])([A-Z])/ That’s two capture groups. /([a-z])([A-Z])/ ↑ capture group 1 /([a-z])([A-Z])/ ↑ capture group 2 Or /([a-z])([A-Z])/ ↑ ↑…