how to tell if variable is nan code example

Example 1: check if something is nan python

import math
print math.isnan(float('NaN'))OutputTrue
print math.isnan(1.0)OutputFalse

Example 2: check if var is NaN

let b=1
let n=readline()
if(isNaN(b)){
  console.log("You typed 0!")
}else{
  console.log("You did not type 0!")
}