check the value is NaN code example
Example 1: python test is nan
math.isnan(n)
Example 2: check if value is NaN
Number.isNaN(123)
Example 3: 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!")
}