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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>