Changing value of one input field based on other.

Question

Hello All,
I am having this interesting situation with changing a value of a INPUT form in jsp based on another INPUT.
Lets say my form has 3 INPUT variables.
1. YEAR (COMBOBOX) (using the SELECT OPTION)
2. MONTH (COMBOBOX)(using the SELECT OPTION)
3. TEXT
If the user sets the year to 2003, I want to show all 12 months. But if the user sets the year to 2004, I want to show only the month of Jan and then not allow the user to change the value.
I also need both these values to go as form input when the user hits submit.
After reading the JSP/Javascript issues other people are having with regard to accessing variables across these two(i.e jsp and javascript), it looks like ther is no easy way to achieve this using
"onChange=setValue()" on the YEAR field.
What would be the best way to do this?
Thanks,
Chhaya

Answer 1

u can use javascript funtion
u can pass day month and year wiich will return false if wrong date was selected like leap year,selecting 31 feb etc.
function validatedate(dd,mm,yy)
          cday=dd
          aday=dd
          cmonth=mm
          cyear=yy
leapyearcal=cyear%400
          if(leapyearcal==0)
               leapyear="OK"
          else
          {     leapyearcal=cyear%100
               if(leapyearcal==0)
                    leapyear="no"
               else
                    leapyearcal=cyear%4
                    if(leapyearcal==0)
                         leapyear="OK"
                    else
                         leapyear="no"
          if ((cmonth==1)||(cmonth==3) || (cmonth==5) || (cmonth==7) || (cmonth==8)|| (cmonth==10) || (cmonth==12))
               aday=31
          if ((cmonth==4)||(cmonth==6) || (cmonth==9) || (cmonth==11))
               aday=30     
          if ((cmonth==2)&& (leapyear=="OK"))
               aday=29
          else if (cmonth==2)
                    aday=28
          if (cday>aday)
                    return true
          else
                    return false
}