Date validation with html5 dates

• enddate should not be less than or equal to startdate.

• startdate should not be less than or equal to the date today unless document.getElementById("ltype").value == "1".

• The maximum gap between startdate and enddate is one year, more than that should cause an error alert.

// creates a date object then converts it to a string with yyyy-mm-dd format
function dateFormat(date, addyear) { // addyear is boolean, true means add another year to the date
    var dd = date.getDate();
    var mm = date.getMonth()+1;
    var yyyy = date.getFullYear();
    if (addyear) {
        yyyy++;
    }
    if(dd yeardate) {
        alert("Dates out of range");
        return false; 
    }
    if (document.getElementById("ltype").value != "1" && startdate <= today) {
        alert("Error! date goes backwards!");
        return false;
    }
    return true
}

• Instead of giving your variables names like dd/mm/yyyy, you should give them names like day, month, year. Other names like d1 or d2. Should have better names.

• You need some space between operators. For example, you have this condition in your code: if(dd

• Finally, just a small nitpicky thing. Both of your functions should be in camelCase. One of them is in underscore_case`.