nextQuery(document).ready(function() { //custom //assumes there is just one date picker on the page jQuery('.nextRegister input[type="date"]').blur(function(){ var dob = jQuery('input[type="date"]').val(); console.log('dob:' + dob); dob = new Date(dob); console.log('dob:' + dob); var today = new Date(); console.log('today:' + today); var age = Math.floor((today-dob) / (365.25 * 24 * 60 * 60 * 1000)); console.log('age:' + age); if(age < 21){ jQuery('input[type="date"]').val(''); alert('You must be at least 21 years old.'); return false; } }) });