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

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

^(([0]?[1-9]|1[0-2])/([0-2]?[0-9]|3[0-1])/[1-2]\d{3}) (20|21|22|23|[0-1]?\d{1}):([0-5]?\d{1})$

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

function validate_date(date_str, date_format){
    /* Validate date or datetime due to specified format
     *
     * Example: date_str "01/01/2016" valid with format "MM/dd/YYYY",
     *          but invalid with format "MM/dd/YYYY hh:mm:ss"
     *
     * NOTE: MM/dd/YYYY and M/d/Y are equivalent, hh:mm:ss equals to h:m:s
     */
    date_str = date_str.trim();
    var date_parsed = Date.parse(date_str);
    if (!isNaN(date_parsed)) {
        date_parsed = new Date(date_parsed);
    } else {
        return false;
    }
    // build date from components according to format
    date_format = date_format.replace(/M+/g, ("0" + (date_parsed.getMonth() + 1)).substr(-2));
    date_format = date_format.replace(/d+/g, ("0" + date_parsed.getDate()).substr(-2));
    date_format = date_format.replace(/Y+/g, date_parsed.getFullYear());
    date_format = date_format.replace(/h+/g, ("0" + date_parsed.getHours()).substr(-2));
    date_format = date_format.replace(/m+/g, ("0" + date_parsed.getMinutes()).substr(-2));
    date_format = date_format.replace(/s+/g, ("0" + date_parsed.getSeconds()).substr(-2));
    console.log(date_parsed);
    console.log(date_format);
    return date_str == date_format
};

alert(validate_date('02/30/2016', 'MM/dd/YYYY'));
alert(validate_date('02/28/2016', 'MM/dd/YYYY'));

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('02/30/2015')); //false  mm/dd/yyyy
alert(validate_date('02/28/2015')); //true  mm/dd/yyyy

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); alert(str)
        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('02/дд/2015')); //  mm/dd/yyyy

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 == 'Invalid Date') 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('02/дд/2015')); //false  mm/dd/yyyy
alert(validate_date('02/30/2015')); //false  mm/dd/yyyy
alert(validate_date('02/29/2016')); //true  mm/dd/yyyy