required input Safari

safari.js

<script type="text/javascript">
        function checkForm(){
            var forms = document.getElementsByTagName('form');
            for (var i = 0; i < forms.length; i++) {
                forms[i].noValidate = true;

                forms[i].addEventListener('submit', function(event) {
                    //Prevent submission if checkValidity on the form returns false.
                    if (!event.target.checkValidity()) {
                        event.preventDefault();
                        //Implement you own means of displaying error messages to the user here.
                        alert('Please, fill the form.');
                    }
                }, false);
            }
        }

    </script>