I am not an expert by any means, but at a first glance, you are reserving extra space with var j, when you could use parameter x directly.

0 x 1 = 0 thats why you can't start at zero. the loop is to generate the values then pushing them to the array.

You need x at z[0]. If i would be 0 your z[0] would be always 0. Multiply by 0 is alwyas 0.

@meditatingCybermind what do you think about .fill(1)and [...Array(n).keys()] ?

I like the way you did yours, I didn't realize I was allowed to change x and y to something else. Also, what does the 'use strict' bit mean?

yeah. also it's not the best practise to call the variables "x", "n" or "z".