jQuery(document).ready(function($){
    if (typeof acf == 'undefined') { return; }

      var acf_field = acf.getField('field_579376f522130');

      acf_field.on("change ready", function(e){

        // bail early if no ajax
        if( !acf.get('ajax') ) return;

        // abort XHR if it's already running
        if( this.request ) {
          this.request.abort();
        }

        // set the ajax action that's set up in php
        var data  =  {
            action: 'load_city_field_choices',
            key_name: acf_field.val(); //The key_name needs to be the name of the parameter in your action
        }

        this.request = $.ajax({
          url:    acf.get('ajaxurl'),  // ajax url, acf already sets this
          data:    acf.prepareForAjax(data), // another included acf function
          type:    'post', // posted values, look at $_POST in your php ajax action function
          dataType:  'json', // how we want the date returned
          success: function( json ){
            // get the field we want to populate
            var $select = $('.acf-field-5793770922131 select');
            // this stores the currenlty selected value in that field
            // so that we can mark it as selected, this is important when loading
            // and exsiting post
            var $selected = $select.val();
            // clear all of the exsiting options from the field
            $select.empty();
            // rebuild the child select field
            $select.append('<option data-i="" selected="selected" value="">- Select -</option>');
            var count = json.length;
            for (i=0; i<count; i++) {
              var $item = '<option value="'+json[i]['value']+'"'
              if ($selected == json[i]['value']) {
                $item += ' selected="selected"';
              }
              $item += '>'+json[i]['label']+'</option>';
              $select.append($item);
            }
          }
        }); // end ajax

      });

      // trigger the ready action to load the field
      // this is important for existing posts
      $('#acf-field_579376f522130').trigger('ready');

  });