JS: Number.isNaN

Number.isNaN(number)

If number is NaN, return true, else false. [see NaN]

console.log(Number.isNaN(NaN));

console.log(Number.isNaN("NaN") === false);
console.log(Number.isNaN("3") === false);
console.log(Number.isNaN(3) === false);
console.log(Number.isNaN(Infinity) === false);