Periksa JavaScript IF NAN
function isNaN(x) {
return x !== x;
};
isNaN(NaN);//true
Grepper
function isNaN(x) {
return x !== x;
};
isNaN(NaN);//truelet b=1
let n=readline()
if(isNaN(b)){
console.log("You typed 0!")
}else{
console.log("You did not type 0!")
}