Can someone explain me how this regex works?

[NeedToLearnFrontEnd]

Hi. So i am on the ‘Spinal Tap Case’ challenge and i am stucked. I sneak peaked the solutin and i cannot really understand the regex which replaces UpperCase with space.

The first regex was easy enough for me to figure it out: let regex = /[\W\s+_]/g;.

But the regex i dont understand is this one: str = str.replace(/([a-z])([A-Z])/g, "$1 $2");

Can someone explain me how this works exactly? Which part of the regex identifies the space we add?

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Challenge: Spinal Tap Case

Link to the challenge:

freeCodeCamp.org

[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])/ ↑ ↑…

[NeedToLearnFrontEnd]

I know understood it! Thank you! I did not understand how we defined the space between them. The space is actually in the script “$1 here:D $2”. Got it, thanks again!