javascript - event.preventDefault(); only works some of the time with submit form -

i using mailchimp api submit form. goal prevent default callback provided mailchimp. majority of time event.preventdefault() behaving should. randomly not work:

$(function () {  var $form = $('#mc-embedded-subscribe-form');  $('#mc-embedded-subscribe').on('click', function(event) {      if(event) event.preventdefault();     register($form);    }); });  function register($form) {     $.ajax({         type: $form.attr('method'),         url: $form.attr('action'),         data: $form.serialize(),         cache       : false,         datatype    : 'json',         contenttype: "application/json; charset=utf-8",         error       : function(err) { alert("could not connect registration server. please try again later."); },         success     : function(data) {         if (data.result != "success") {             // went wrong, notify user. maybe alert(data.msg);             var message = data.msg             var messagesh = data.msg.substring(4);             if (data.msg == '0 - please enter value' || data.msg == '0 - email address must contain single @') {                $('#notification_container').html('<span class="alert">'+messagesh+'</span>');              } else {                 $('#notification_container').html('<span class="alert">'+message+'</span>');             }         } else {             // worked, carry on...         var message = data.msg;         $('.popup-promo-container').addclass('thanks');         $('.checkboxes, #mc_embed_signup_scroll').addclass('hidden');         $('.complete-promo').html(message).removeclass('hidden');         settimeout(function() {             document.queryselector('.popup-promo').style.display = "none";         },20000);          }     } }); } 

try

1. take off ready function.
2. remove if on event

code:

var $form = $('#mc-embedded-subscribe-form');  $('#mc-embedded-subscribe').on('click', function(event) {     event.preventdefault();     register($form); });