Where trigger the “Please enter a valid date.” in jquery.validate.js

Question

I am using jQuery UI version 1.12.1 and jQuery Validation v1.15.0

I created a datepicker as follow:

if ($.fn.datepicker) $(\':input.date\').datepicker({
         


        

Answer 1

Found it, it was actually trigger by a date method validation in jquery.validate.min.js, which is in line 1356:

// http://jqueryvalidation.org/date-method/
        date: function( value, element ) {
            return this.optional( element ) || !/Invalid|NaN/.test( new Date( value ).toString() );
        },