Why can’t I add one day in to a day object in JavaScript?

Why does this work?

<script>

            var today = new Date();
            var yesterday = new Date(Date.now() - 24*60*60*1000);

            from.max = yesterday.toISOString().split("T")[0];
            to.max = today.toISOString().split("T")[0];

            $(document).ready(function () {
            $("#from").change(function () {
            var minDate = $("#from").val();

            var fromDate = new Date(minDate);
            var minToDate = new Date(fromDate - 24*60*60*1000);
            
            $('#to').attr('min', minToDate.toISOString().split("T")[0]);

            });
            });

        </script>

But this does not:

... var minToDate = new Date(fromDate + 24*60*60*1000); ...

The point is to set the minimum date of “to” to the next day of the chosen “from” date. Just for testing purposes I tried the “-” version. And it truly sets the minimum value to the day before the “from” date. But the opposite, which is what I’m looking for, is not working. Crazy! 😀