@myjinxin2015 version looks slick af, but it is quite slow performance wise. Your ( @hei-yu-fa ) code does not look that good, but is twice as fast. It all comes down to what you are after.

@myjinxin2015 timed at 3870.2 milisec when called for nNumber = 5000
@hei-yu-fa timed at 1972.2 milisec when called for nNumber = 5000

ah yeah the sorting.............................real headache

It's a clever utilization of the comma operator to compress all the stuff into a one-liner. The comma operator just evaluates both its sides and returns the right hand one, so here it allows for assigning to a property of an object but returning the entire object instead of just the property. Also, look at the assignment string: it's not enclosed in apostrophes but backticks, so it's a template literal.

Currently Codewars platform has lots of issues. It's not a problem of this kata. See:

https://github.com/Codewars/codewars.com/issues/893

Wow! That's some hardcore coding!
Still... you solved this challenge in a completely different way, and learned of other approaches. If you learned something in the process, then Achievement Unlocked! ^^

I took around 90 lines of code .. this broke my heart. brute force method to the point of not even being proud lol.
You have taught me I know nothing in JS yet

Yeah, don't worry about it. It takes time to learn all the tricks of the trade ^^

learning and training ;-)