function isValidDate(){
    var date = parseFloat(document.getElementById('date').value);
    check = /^([0-9]){2})-([0-9]{2})-([0-9]{4})$/;

    if(!date.match(check)){
        alert("Error:Date format wrong: ##-##-####");
        return false;
    }else{
        //it only will works if the  date will be exacly 00-00-0000  /  00/00/0000
        // get all the caracters bettween one string index's link below
        //https://www.w3schools.com/jsref/jsref_substr.asp

        var dateDay = parseInt(date.substr(0,2));
        var dateMonth = parseInt(date.substr(2,4));
        var dateYear = parseInt(date.substr(5,9));
        // This year that will be registred is a leap year ?
        var leapYear = false; // Starts with false  but needs to have comparison
        if( (dateYear % 400 == 0) || (dateYear % 4 == 0   && dateYear % 100 == 0) )
        {
            leapYear = true;
        }else{
            leapYear = false;
        }

        var daysInMonth;
        //4,6,9,11  daysInMonth = 30 if the month is April, June, September, or November
        if(dateMonth == 4 || dateMonth == 6 || dateMonth == 9|| dateMonth == 11)
        {
            daysInMonth = 30;
        }// ... others if for all months
        //  needs to make others decision and make  the data format verification
        //in date.match(check())... improved
    }
}