function Validator() {}

Validator.min = function(number, min) {
    return number >= min;
}

Validator.max = function(number, max) {
    return number <= max;
}

Validator.between = function(number, min, max) {
    return Validator.min(number, min) && Validator.max(number, max)
}

/**
 * dd/mm/yyyy validation
 * @param  {string} date
 * @return {boolean}
 */
Validator.date = function(date) {
    var regex = /^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$/;
    if (!regex.test(date)) return false;

    var pdate = date.split('/');
    if (pdate.length < 3) pdate = date.split('-'); // if separator is not '/'
    if (pdate < 3) return false; // check if array length < 3

    var d = parseInt(pdate[0]);
    var m = parseInt(pdate[1]);
    var y = parseInt(pdate[2]);
    var daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

    if (!Validator.between(m, 1, 12)) return false;

    if ((!(y % 4) && y % 100) || !(y % 400)) {
        daysInMonth[1] = 29; // leap year
    }

    return d <= daysInMonth[--m];
}