Javascript: Validate Date

Put this code in the script tag under head tag.

var dtCh= “/”;
var minYear=1900;
var maxYear=2100;

function isInteger(s){
var i;
for (i = 0; i < s.length; i++){
// Check that current character is number.
var c = s.charAt(i);
if (((c “9″))) return false;
}
// All characters are numbers.
return true;
}

function stripCharsInBag(s, bag){
var i;
var returnString = “”;
// Search through string’s characters one by one.
// If character is not in bag, append to returnString.
for (i = 0; i < s.length; i++){
var c = s.charAt(i);
if (bag.indexOf(c) == -1) returnString += c;
}
return returnString;
}

function daysInFebruary (year){
// February has 29 days in any year evenly divisible by four,
// EXCEPT for centurial years which are not also divisible by 400.
return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}
function DaysArray(n) {
for (var i = 1; i 1) strDay=strDay.substring(1)
if (strMonth.charAt(0)==”0″ && strMonth.length>1) strMonth=strMonth.substring(1)
for (var i = 1; i 1) strYr=strYr.substring(1)
}
month=parseInt(strMonth)
day=parseInt(strDay)
year=parseInt(strYr)
if (pos1==-1 || pos2==-1){
alert(“The date format should be : mm/dd/yyyy”)
return false
}
if (strMonth.length<1 || month12){
alert(“Please enter a valid month”)
return false
}
if (strDay.length<1 || day31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
alert(“Please enter a valid day”)
return false
}
if (strYear.length != 4 || year==0 || yearmaxYear){
alert(“Please enter a valid 4 digit year between “+minYear+” and “+maxYear)
return false
}
if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
alert(“Please enter a valid date”)
return false
}
return true
}

function ValidateForm()
{
//Give your textbox name here
var dt = document.getElementById(“TextBoxName”).value;
if (isDate(dt)==false){
document.getElementById(“txtDate”).focus()
return false
}
return true
}

From the html body part call the javascript function ValidateForm()

form name=”frmSample” method=”post” action=”" onSubmit=”return ValidateForm()”

Thanks,
Anil.