25) What does the isNaN() function?

The isNan() function returns true if the variable value is not a number. For example:

function number(num) {
if (isNaN(num)) {
return “Not a Number”;
}
return “Number”;
}
console.log(number(‘1000F’));
// expected output: “Not a Number”

console.log(number(‘1000’));
// expected output: “Number”