How do i check for "NaN"

1

I’ve got to write to a db table (using Zinc) and the field requires a data type of Number. In my application, the user enters a string, which could be letters in which case I’ll throw an error.

So far, im using Number(a) to convert to a number, but if the string wasn’t a number, I of coarse get “NaN”.

But how do i do a conditional that checks for NaN?

b = Number(a)

if(b == NaN) …this doesn’t work
if(b == “NaN”) also doesn’t work nor does
if(b == Number.NaN)

Maybe theres a better way to check for a number, if so, please let me know

Thanks!