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!")
}