<script language="JavaScript">
function FormatDate(InpDate)
{
if(InpDate == "")
{
alert("Enter the Date field");
return false;
}
else
{
if(InpDate.length < 8)
{
alert("Enter Correct Date")
return false;
}
else
{
InpVal = InpDate;
SendNext = "False";
PrevSlash = "";
LastSlash = "";
for(i = 0;i <= InpDate.length-1;i++)
{
PrevSlash = LastSlash;
LastSlash = InpDate.substring(i,i+1);
if((LastSlash == '/' && i == 0 ))
{
alert("Your Date Format is incorrect");
return false;
break;
}
if ((LastSlash == '/' || LastSlash == '.') && (PrevSlash == '.' || PrevSlash == '/'))
{
alert("Your Date Format is incorrect");
return false;
break;
}
else
{
if (LastSlash == '/' || LastSlash == '.')
SendNext = "True";
}
}
if (SendNext == "True")
{
lBool="False";
LMonth="False";
LDate="False";
var OutVal;
var InVal;
var RoundYear;
var Mon;
var LastSlashNumber;
var j;
var k;
var x;
x = InpDate;
OutVal="";
TotVal="";
LastSlashNumber=0;
for(i = 0;i <= x.length-1;i++)
{
LastSlash = x.substring(i,i+1);
if (LastSlash != 0 && LastSlash != 1 && LastSlash != 2 && LastSlash != 3 && LastSlash != 4 && LastSlash != 5 && LastSlash != 6 && LastSlash != 7 && LastSlash != 8 && LastSlash != 9 && LastSlash != '/' && LastSlash != '.') //fifth if
{
lBool="True";
break;
}
else
{
if (LastSlash == '/' || LastSlash == '.' || LastSlashNumber == 2 ) //sixth if
{
InVal = OutVal;
if (InVal == '0' || InVal == '00' || InVal == '0000') //seventh if
{
alert("You entered Some Zero's in the field(Month/Date/Year)")
return false;
break;
}
TotVal = TotVal+InVal
OutVal="";
if (LastSlashNumber == 0 )
{
LastSlashNumber = LastSlashNumber + 1;
Mon = InVal;
if (InVal > 12)
{
LMonth ="True";
InVal="";
break;
}
}
else
{
if(LastSlashNumber == 1)
{
Dat = InVal;
LastSlashNumber = LastSlashNumber + 1;
if(Mon == '01' || Mon == '1' || Mon == '03' || Mon == '3' || Mon == '05' || Mon == '5' || Mon == '07' || Mon == '7' || Mon == '08' || Mon == '8' || Mon == '10' || Mon == '12')
{
if (InVal > 31)
{
LDate ="True";
InVal="";
break;
}
}
else
{
if(Mon == '04' || Mon == '4' || Mon == '06' || Mon == '6' || Mon == '09' || Mon == '9' || Mon == '11')
{
if (InVal > 30)
{
LDate ="True";
InVal="";
break;
}
}
}
}
else
{
if(LastSlashNumber == 2 )
{
LastSlashNumber = LastSlashNumber + 1;
lYear = x.substring(TotVal.length+2,x.length);
if(lYear == '0000')
{
alert("You entered Some Zero's in the field(Month/Date/Year)")
return false;
}
else
{
if(lYear.length <= 3 )
{
alert("Enter Four digits for Year");
return false;
break;
}
else
{
if(lYear.length > 4 )
{
alert("Enter Four digits for Year");
return false;
break;
}
else
{
RoundYear = Math.round(lYear/4);
if (lYear/4 != RoundYear)
{
if(Mon == 2 && Dat > 28 )
{
alert("You entered More than 28 in the date field (it's not a leap year)");
return false;
break;
}
else
{
alert("Entered Date is Correct");
return true;
}
}
else
{
if(Mon == 2 && Dat > 29)
{
alert("You entered More than 28 in the date field/month is febraury");
return false;
break;
}
else
{
alert("Entered Date is Correct");
return true;
}
}
}
}
}
}
else
{
alert("Entered Date is Correct");
return true;
}
}
}
}
else
OutVal=OutVal + LastSlash;
}
}
}
else
{
alert("You Date format is incorrect");
return false;
}
}
}
if (lBool == "True")
{
alert("You entered some alpha value in the Date field");
return false;
}
else
{
if (LMonth == "True")
{
alert("Your Month is invalid");
return false;
}
else
{
if (LDate == "True")
{
alert("Your Date is invalid");
return false;
}
else
{
alert("Entered Date is Correct");
return true;
}
}
}
}
</script>
<HEAD>
<BODY>
<table width=100%>
<tr><td valign=top>
<h2>Validate Date</h2>
<form name="frmDate">
<b><font face=Verdana color=indigo size=2>
(Format mm/dd/yyyy or mm.dd.yyyy)</font><br>
<input name="dtDate"><br>
<input type="button" value="CheckDate" OnClick="JavaScript
:FormatDate(frmDate.dtDate.value)">
</form>
Before you post, read our: 
Date Validation
