问jQuery事件只触发一次，然后就不再发生了。

EN

<select id="connection" name="Connection"></select>
<div id="testme" style="background: #CCC; width:100%; height:50px;position:relative;color:red">testing</div>

$(document).ready(function () {
    // Event handler. Tried as a separate function and as a parameter to $.on(...)
    function connectionSelected() {
        var str = $('#connection option:selected').text();
        alert(str);
        $("#testme").text(str);
    }

    var $connectionSelect = $('#connection');
    //$connectionSelect.selectmenu(); // Tried enabling/disabling

    // Tried this and all JS code inside and outside of $(document).ready(...)
    $.when(
    $.ajax({
        dataType: "JSON",
        url: '@Url.Content("~/API/ConnectionHint")', // The AJAX call (using ASP Razor) works fine
        success: function(data) {
            // This function is always called and works
            var items = [];
            $.each(data, function(key, val) {
                items.push("<option value='" + key + "'>" + val + "</option>");
            });
            $connectionSelect.append(items.join(""));
            // Tried setting up the event handler here
        },
        error: function() {
            $connectionSelect.html('<option id="-1">none available</option>');
        }
    })
    ).then(function() {
        //$("#connection option").blur(connectionSelected()).change();
        $("#connection").on("change", connectionSelected());
    });
});

$connectionSelect.selectmenu({
    change: function (event, data) {
        $('#connection').change(function () {
            var str = "";
            $('#connection').each(function () {
                str += $(this).text() + "<br>";
            });
            $("#testme").text(str);
        });
    }
});