Is-Number Node Module

And the corresponding source code [0]

  if (typeof num === 'number') {
    return num - num === 0;
  }
  if (typeof num === 'string' && num.trim() !== '') {
    return Number.isFinite ? Number.isFinite(+num) : isFinite(+num);
  }
  return false;

[0]: https://github.com/jonschlinkert/is-number/blob/master/index...