isn't it easy to read and understand to write "function". I know its easy to write arrow function, but for me the classic way is much more simpler to understand and read.

whole numbers, integers, and decimals, floats, are different kinds of numerical data. There is no need to worry about floats because that isnt the data being tested.

genius! I was stuck on this one for hours

yeah should be defensive

integers do not involve decimals... what if someone kept a decimal as an argument.
what do you think about flooring the return value?

it can get more compact if you turn it into an arrow function

How does this work?

nice!

About as simple as it gets!

а ты хорош)

Thank you

This is an absolutely great write up and I really appreciate you taking the time to write all that down for us!

still applies...

Please explain how this works.

Usually I'd suggest to write the return in the same line after the if instead to better indicate it's an if body that is valid for one line only. Never forget that goto fail bug ;-)