Can someone explain me how this regex works?

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:

you can try to review this challenge:

you can also take a look at this explanation:

and this follow up:


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!

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