Can not stop submit event in Javascript

Quân Trần Văn :

I used this to validate my form but I can stop the submit event on my page. It still sends data and submit that. Why? How can I stop it?

    $(document).on("submit", "form", function(e) {
        if ($('#input-name').val() === '' && $('#input-phone-number').val() === '' && $('#input-address').val() === '' && $('#input-email').val() === '') {
            e.preventDefault();
            $('.noti-container').css({
                'opacity': '1',
                'z-index': '9999',
                'top': '20px',
                'background': '#FFCCCC'
            });
            $('.icon-container').html('<i class="fa fa-close"></i>');
            $('.notif').text('Please fill all field!');
            $('.notif').css({'color': 'black'});
            $('.icon-container').css({
                'background': '#F2F5A9'
            });
            setTimeout(function () {
                $('.noti-container').css({
                    'opacity': '0',
                    'z-index': '-1',
                    'top': '0',
                })
            }, 1500);
            return false;
        } else {
            return true;
        }
    });

Sudharsan Ravikumar :

e.preventDefault(); seems to be present in the if block. If the if condition resolves to false, the form will be submitted. You need to move e.preventDefault(); code before if block to prevent submission on all cases.

Example:

$(document).on("submit", "form", function(e) {
  e.preventDefault();
  // Remaining Code
}