提交AJAX发布变更

I'm trying to figure out why this isn't working, I don't want to have a submit button to click, It does work if I have one though, instead I use onchange="this.form.submit()" and that posts the form as it normally would, not AJAX background style, I didn't code the ajax part, I found it and made it work for my situation, but as far as I know $('#ajaxform').submit(function (), submit is submit? Why isn't onchange="this.form.submit()" and <input type="submit" /> the same type of submit? What am I missing?

    <form method="post" action="~/getAJAX.cshtml" id="ajaxform" name="form">
        @* -------- Div to hold form elements -------- *@
        <div class="reportDateDiv">

            @* -------- Text --------- *@
            <a class="blackColor fSize18 RPtxt">Reporting Period</a>

            @* -------- Start day box -------- *@
            <input type="text" name="inputDate" spellcheck="false" class="datepickerS metricDateTextbox capitalFirst"
                  onchange="this.form.submit()" value="@inputDate" autocomplete="off" placeholder="@placeholderStartDate.ToString("MMM d, yyyy")" readonly="readonly" />

            @* -------- Text --------- *@
            <a class="blackColor fSize16 RPtxt RPtxtTo">to</a>

            @* -------- End day box --------- *@
            <input type="text" name="endDate" spellcheck="false" class="datepickerE metricDateTextbox capitalFirst"
                  onchange="this.form.submit()" value="@endDate" autocomplete="off" placeholder="@noEndDate.ToString("MMM d, yyyy")" readonly="readonly" />

        </div>
    </form>

    <script type="text/javascript">
        $('#ajaxform').submit(function () { // catch the form's submit event
            $.ajax({ // create an AJAX call...
                data: $(this).serialize(), // get the form data
                type: $(this).attr('method'), // GET or POST
                url: $(this).attr('action'), // the file to call
                success: function (response) { // on success..
                    $('#here').html(response); // update the DIV
                }
            });
            return false; // cancel original event to prevent form submitting
        });
    </script>