'looks like you solved it'

[a,b], yes.

Great, it's now working and I have marked it as spoiler. Thank you.

Square Every Digit

Where are you squaring anything? And next time, please, mark your post as having spoiler content. You also have a double dot there.

Awesome. I get you. I couldn't think of a way of adding arguments to an array. Can I say [...a,b] or [a,b]?

• thing is: the arguments are already available (a and b) so why are you using it? (the arguments thing, I mean)
• keep things simple. You don't need that arr thing, just a number that you'll update, then return in the end.

1. What can I use instead of arguments?

2. It should have been reduced, thank you.

3. My biggest confusion is if I can have #for after else statement.

• why do you use arguments? Don't use that... It's old fashion and the best way to do bad things.
• replace isn't a method of Array.prototype => ???
• actually, you're applying replace to the output of push, which is a number... (see MDN documentation) => ???!??

Read the docs of the methods you're trying to use, you're doing it wrong, and why are you using parseInt?