[рони]

Master_Sergius,

function validate_date(date) {
    var str = date.trim().split("/");
    if (str.length == 3) {
        str = new Date(str[2], str[0] - 1, str[1], 0, 0, 0);
        if (!str) return false;
        str = [("0" + (str.getMonth() + 1)).substr(-2), ("0" + str.getDate()).substr(-2), str.getFullYear()].join("/");
        return str === date.trim()
    }
    return false
};
alert(validate_date('01/21/2015')); //true  mm/dd/yyyy
alert(validate_date('40/40/2015')); // false