### Validate number Use `!isNaN` in combination with `parseFloat()` to check if the argument is a number. Use `isFinite()` to check if the number is finite. Use `Number()` to check if the coercion holds. ```js const validateNumber = n => !isNaN(parseFloat(n)) && isFinite(n) && Number(n) == n; // validateNumber('10') -> true ```