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This is the most simple way to do a JavaScript date validation. I usually call this onBlur, because I only want to check it if the user fills it in. If it's blank, I just pass it up.
// this section goes in your form:
//<input type="text" onBlur="return checkDate(this.value);">
//Put the following in <HEAD> section:
<script language="JavaScript"><!--
function checkDate(theDate) {
// If the value is not blank, validate the date.
// using isNaN (is not a number) and date parse.
// If the date is invalid, give the user an alert
// message, set the form focus to the date field.
// and return false. If it's valid then return true.
if (theDate!= "") {
if (isNaN(Date.parse(theDate))) {
alert("Please enter yourDate in mm/dd/yy format.");
return false;
} else {
return true;
}
}
}
--></script>