$.ajax({

    url: "test.aspx?action=testaction",

    contentType: "application/json; charset=utf-8",

    dataType: 'json',

    type: 'GET',

    data: JSON.stringify({name:''}),

    error: function (data, status, e) {

        $("#loadingDialog").dialog('close');

        alert(e);

    },

    success: function (data) {

        // data is json

        $("#loadingDialog").dialog('close');

        showResult(data);

    },

});