I wouldn't recommend the isNaN function to detect numbers, because of the Java Script type coercion.

Ex:

isNaN(); // returns false (is number), a empty string == 0

isNaN(true); // returns false (is number), boolean true == 1

isNaN(false); // returns false (is number), boolean false == zero

isNaN(new Date); // returns false (is number)

isNaN(null); // returns false (is number), null == 0 !!

You should also bear in mind that isNaN will return false (is number) for floating point numbers.

isNaN('1e1'); // is number

isNaN('1e-1'); // is number

I would recommend to use this function instead:

function isNumber(n) {

  return !isNaN(parseFloat(n)) && isFinite(n);

}