https://diit.cz/sites/all/modules/contrib/entityreference/js/entityreference.js?tk0e51

1(function ($) {
2    'use strict';
3    Drupal.behaviors.ACChangeEnterBehavior = {
4        attach: function (context, settings) {
5            $('input.form-autocomplete', context).once('ac-change-enter-behavior', function() {
6                $(this).keypress(function(e) {
7                    var ac = $('#autocomplete');
8                    if (e.keyCode == 13 && typeof ac[0] != 'undefined') {
9                        e.preventDefault();
10                        ac.each(function () {
11                            if(this.owner.selected == false){
12                                this.owner.selectDown();
13                            }
14                            this.owner.hidePopup();
15                        });
16                        $(this).trigger('change');
17                    }
18                });
19            });
20        }
21    };
22}(jQuery));